fBRARY 
PSYCH 


:: 


^m^^m^ 


THE  FUNDAMENTALS 
OF  PSYCHOLOGY 


THE  MACMILLAN  COMPANY 

NEW  YORK    ■     BOSTON    •    CHICAGO 
DALLAS    •    ATLANTA    •    SAN   FRANCISCO 

MACMILLAN  &  CO..  Limited 

LONDON    ■     nOMBAY    ■    CALCUTTA 
MELBOURNE 

THE  MACMILLAN  CO.  OF  CANADA,  Ltd. 

TORONTO 


THE  FUNDAMENTALS 
OF  PSYCHOLOGY 


BY 
W.  B.  PILLSBURY 

PROFESSOR  OF  PSYCHOLOGY 

DIRECTOR  OF  THE  PSYCHOLOGICAL  LABORATORY 

UNIVERSITY  OF  MICHIGAN 


REVISED  EDITION 


THE  MACMILLAN  COMPANY 
1922 

All  rights  reserved 


PRINTED   IN   THE   UNITED   STATES  OF   AMERICA  '  ^  ' 

^OGY 


COPTBIGHT,    1916   AND    1922, 

By  THE  MACMILLAN  COMPANY. 


Revised  Edition.    Set  up  and  electrotypsd 
Published  September,  1922. 


Press  of  J.  J.  Little  &.  Ives  Co. 
New  York 


PSYCH. 


PREFACE    TO    THE    REVISED    EDITION 

In  the  present  revision  I  have  made  numerous  changes  in 
expression,  have  modified  several  sections  that  proved  un- 
necessarily difficult  for  students,  and  have  brought  the  sub- 
ject matter  up  to  date.  The  major  changes  consist  in  the 
introduction  of  three  entirely  new  chapters.  One  of  these 
considers  the  differences  in  individuals  at  birth,  and  presents 
the  methods  of  measuring  intelligence,  and  the  hereditary 
conditioning  of  intelHgence.  This  chapter  also  gives  a  pre- 
liminary discussion  of  the  laws  of  learning.  To  complete 
the  discussion  of  the  innate  differences,  the  chapter  on  In- 
stinct has  been  brought  forward  from  the  latter  part  of  the 
book.  The  two  other  new  chapters  discuss  respectively  Im- 
agination and  Dreams,  with  some  reference  to  Freud,  and 
Fatigue  and  Sleep. 

In  the  revision  I  have  been  much  aided  by  suggestions 
from  teachers  in  many  institutions  who  have  used  the  book, 
and  especially  by  my  colleagues  and  Dr.  A.  H.  Sutherland. 
I  desire  to  express  my  thanks  to  all  of  them  named  and 
unnamed. 

W.    B.   PILLSBURY. 

Ann  Arbor,  Michigan, 
August,  1922. 


504872 


PREFACE   TO   THE   FIRST   EDITION 

This  book  is  intended  to  fill  a  gap  which  exists  to-day 
between  the  smaller  texts  and  the  reference  hand-books. 
I  have  had  in  mind  the  needs  of  one  of  my  own  classes 
which  devotes  a  year  to  psychology  and  includes  students 
who  have  had  no  previous  work  in  the  subject.  They  have 
more  than  time  to  cover  the  present  texts  but  are  lost  in 
the  details  of  the  larger  works,  particularly  in  connection 
with  the  nervous  system,  sensation,  and  perception. 

I  have  written  for  the  student  primarily  and  have  not 
presupposed  any  preliminary  knowledge.  I  have  particu- 
larly avoided  reference  to  current  theories  before  they  are 
explained  and  have  indulged  in  no  arguments  on  controver- 
sial matter  for  the  benefit  of  colleagues  rather  than  of  the 
student.  Opposing  theories  are  discussed  only  as  they  may 
illumine  statements  of  fact  or  where  they  have  great  his- 
torical importance  and  then  only  if  the  problem  is  real  but 
is  not  settled. 

The  technical  psychologist  may  miss  long  discussions  of 
general  method  and  points  of  view  I  have  replaced  them 
by  fuller  statements  of  the  results  of  experiment  and  more 
detailed  treatment  of  the  generally  accepted  body  of  facts. 
I  have  drawn  upon  the  work  of  all  schools  without  reference 
to  the  theories  that  the  workers  held,  and  have  stated  the 
results  in  terms  that  seemed  most  suitable  to  the  particular 
material.  Sensation  and  perception  are  discussed  in  struc- 
tural terms,  action  of  all  sorts  in  behavioristic  terms.  This 
gives  some  inconsistencies,  but  they  are  preferable  to  the 


viii         PREFACE  TO  THE  FIRST  EDITION 

awkward  phrases  that  would  result  from  using  the  termi- 
nology of  any  school  to  the  exclusion  of  the  others. 

My  own  theory  inclines  towards  a  functionalism.  The 
book  is  more  concerned  with  what  consciousness  does  than 
with  what  it  is.  As  opposed  to  the  extreme  behaviorism, 
however,  I  am  not  concerned  alone  with  understanding  the 
movements  of  the  organism  and  the  function  of  the  move- 
ments, but  also  with  understanding  knowledge  and  the  way 
in  which  it  develops.  It  is  my  belief  that  the  content  of  the 
science  is  the  same  whatever  the  point  of  view  from  which 
the  subject  be  approached,  and  that  this  content  is  essential 
and  changes  slowly  and  then  through  growth.  The  theories 
are  less  important  and  hkely  to  change  from  decade  to  dec- 
ade. In  contrast  with  some  of  the  recent  authors  I  have 
endeavored  to  supply  the  content  and,  while  I  have  stated 
my  own  theories  in  some  detail,  have  attempted  to  be  suffi- 
ciently undogmatic  to  give  the  instructor  opportunity  to 
develop  his  own  point  of  view. 

I  take  pleasure  in  acknowledging  the  help  that  has  been 
given  in  the  preparation  of  the  manuscript  by  Dr.  Adams, 
Miss  Perkins,  and  my  wife.  All  have  read  the  manuscript 
or  portions  of  it  and  have  made  numerous  suggestions.  The 
latter  has  also  aided  with  proofs  and  index.  Dr.  Huber  has 
aided  much  in  the  selection  of  illustrations  for  the  neuro- 
logical portions,  and  at  his  suggestion  Mr.  Atwell  of  his  lab- 
oratory has  drawn  sections  for  Figures  19,  21,  23,  24,  25, 
and  26.    I  express  my  gratitude  to  both. 

I  also  desire  to  thank  the  individuals  and  publishers  who 
have  permitted  me  to  reproduce  cuts:  Professor  Jennings 
for  cuts  from  his  "Behavior  of  Lower  Organisms,"  Dr.  Bar- 
ker for  illustrations  from  his  "Nervous  System,"  W.  B. 
Saunders  &  Co.  for  figures  from  Howell's  "Text-book  of 
Physiology"  and  Ruber's  "Histology,"  to  Rebmann  Bros. 


PREFACE   TO   THE    FIRST   EDITION         ix 

for  cuts  from  Bing's  ''Regional  Diagnosis,"  and  to  The 
Macmillan  Co.  for  cuts  from  Titchencr's  "Text-book  of 
Psychology,"  from  Thorndike's  "Animal  Mind,"  and  Fos- 
ter's "Physiology." 

W.    B.    PiLLSBURY. 

Ann  Arbor,  Michigan, 
April  25,  1916. 


TABLE    OF    CONTENTS 

Chapter  ^«^^ 

I.  INTRODUCTION i 

Nature  of  Psychology 2 

Scope  of  Psychology 8 

Subdivisions  of  Psychology 11 

II.  THE  NERVOUS  SYSTEM 15 

Behavior  of  Lower  Organisms 15 

Nerve-cells  in  Man 19 

General  Plan  of  the  Nervous  System       .     .  24 

Spinal  Cord 39 

Brain  Stem 46 

Paths  in  the  Brain  Stem 48 

Cerebellum,  Corpora  Quadrigemina,  and  Thal- 

Mus 57 

HI.     THE  NERVOUS  SYSTEM  (continued)   ....  60 

Functions  of  the  Cerebrum 60 

Synapse 77 

Interaction  of  Iaipulses 81 

Consciousness 83 

Autonomic  Nervous  System 84 

Ductless  Glands 85 

Body  and  Mind 88 

IV.     SENSATION 93 

General  Remarks 93 

Vision 97 

Structure  of  the  Eye 98 

Sensatiotis  of  Light 109 

V.     SENSATION  (continued)      ." 136 

Audition 136 

Structure  of  the  Ear 136 

Sensations  of  Tone 142 

xi 


xii  TABLE   OF    CONTENTS 

Chapter  Page 

V.     SENSATION  (continued) 

Tactual  Sensations 157 

Temperature 158 

Pressure  and  Pain 162 

Sensations  of  Taste 170 

Sensations  of  Smell 176 

Kinesthetic  Sensations 181 

Sense  of  Equilibrium 183 

Organic  Sensations 188 

Doctrine  of  Specific  Energies 190 

Studies    in    Sensation    Intensities  —  Weber's 

Law 193 

VI.    THE  ORIGINAL  NATURE  OF  MAN,  AND  THE 

MEANS  OF  MODIFYING  BEHAVIOR    .      .  199 

Intelligence  Tests 202 

Character  Tests 207 

Individual  Differences 208 

Habit  Formation 212 

VII.    INSTINCT 219 

Nature  of  Instinct 219 

Specific  Instincts 224 

Instinct  and  Conduct 233 

Origin  of  Instinct 237 

VIII.    RECALL  AND  THE  QUALITIES  OF  RECALLED 

EXPERIENCES 241 

Retention 242 

Association 246 

Images,  or  Centrally  Aroused  Sensations  .     .  254 

Imagery  Types 258 

IX.     ATTENTION 265 

Nature  of  Attention 265 

Motor  Aspects  of  Attention 268 

The  Limits  of  Attention 273 

Conditions  of  Attention 277 

Attention  and  Association 284 

Forms  of  Attention 288 

Physiological  Basis  of  Attention     ....  291 


TABLE   OF   CONTENTS  xiii 

Chapter  ^"S^ 

X.     PERCEPTION 294 

General  Remarks 294 

Perception  of  Space 298 

Auditory  Space 325 

Illusions  in  Space  Perception 329 

XL     PERCEPTION  (continued) 344 

Perception  of  Movement 344 

Rhythm 349 

Perception  of  Time 352 

General  Laws  of  Perception 356 

XII.    MEMORY 365 

Memory  of  Objects  and  Events 366 

Rote  Memory 368 

Laws  of  Learning 369 

Retention  and  Forgetting 380 

Recall 3^4 

Recognition 3^7 

Meaning  an  Aid  to  Memory 397 

General  Aspects  of  Memory 401 

XIII.     REASONING 407 

Meaning 410 

Concepts 4^4 

Initiation  of  the  Reasoning  Process     .     .     .  424 

Judgment 424 

Inference 427 

Belief  and  Proof 43° 

General  Remarks  on  Reasoning 437 

XIV.     BIAGINATION  AND  DREAMS 44i 

Play 442 

Revery 444 

The  Unconscious 446 

Dreams 448 

Other  Experiences  of  the  Unconscious  and  a 

Critique  of  Freud's  Theory 45 1 

Art 454 

General  Remarks  on  Imagination     ....  4S6 


xiv  TABLE   OF    CONTENTS 

Chapter  Page 

XV.     FEELING  AND  AFFECTION 458 

Affection 460 

Other  Aspects  of  Feeling 468 

Theories  of  Feeling 474 

XVI.    EMOTION  AND  TEMPERAMENT       ....  480 

Characteristics  of  Emotion 481 

Bodily  Responses  in  Emotion 487 

General  Aspects  of  Emotion 494 

Other  Mental  States  Related  to  Emotion  503 

XVII.     GENERAL  PRINCIPLES  OF  ACTION,  AND  THE 

WILL 50S 

Learning 510 

Movement 520 

Choice 528 

The  Will 531 

XVIII.    WORK,  FATIGUE,  AND  SLEEP 538 

Work 538 

Fatigue 541 

Sleep 556 

XIX.    THE  SELF 560 

Nature  of  the  Self 561 

Continuity  of  the  Self 572 

Dissociations  of  the  Self 575 

The  Self  as  the  Whole  Man  Active     .     .     .  579 

Index  of  Names 583 

Subject  Index 586 


THE  FUNDAMENTALS 
OF  PSYCHOLOGY 


FUNDAMENTALS    OF 
PSYCHOLOGY 


CHAPTER  I 
INTRODUCTION 

It  is  easier  to  say  what  psychology  discusses  and  to 
point  out  the  ends  of  its  discussions  than  to  give  a  formal 
definition.  Psychology  is  the  science  which  deals  with  the 
activities  commonly  known  as  mental,  the  processes  of 
perceiving,  of  remembering,  of  thinking,  and  particularly 
with  the  acts  of  the  individual.  As  in  any  other  science, 
the  aim  is  first  to  determine  what  these  activities  are,  what 
they  do,  and  then  to  trace  them  to  their  conditions,  to  un- 
derstand them  in  the  light  of  every  fact  that  can  have  any 
bearing  upon  them.  It  is  easier  to  show  what  psychology 
is  and  what  its  aims  are  by  concrete  illustration  than  by 
abstract  statements. 

Take  memory,  for  example.  Psychology  is  concerned 
with  knowing  all  that  is  possible  of  how  we  learn  and 
remember.  Every  one  is  famihar  with  memory  in  a  purely 
objective  way.  A  lesson  is  studied  and,  when  occasion 
arises,  much  of  it  can  be  repeated.  How  one  remembers, 
troubles  the  ordinary  individual  very  Kttle.  When  ques- 
tioned he  knows  almost  as  Httle  of  how  he  remembers  as 
does  the  questioner.  The  task  of  psychology  is  to  discover 
the  laws  and  conditions  of  learning  and  recall  in  all  of  their 
details.    It  must  know  what  methods  lead  most  certainly 


2  FUNDAMENTALS    OF   PSYCHOLOGY 

and  quickly  to  a  first  learning,  what  kind  of  learning  will 
permit  retention  for  the  longest  time,  and  how  forgetting 
takes  place.  These  investigations  have  been  carried  out  in 
great  detail,  as  will  be  seen  in  a  later  chapter.  While  mem- 
ory itself  is  regarded  as  a  mental  process,  the  measurements 
of  memory  are  as  objective  as  are  measurements  of  the 
strength  of  materials,  although  of  course  the  variation  is 
greater  from  measurement  to  measurement.  The  experi- 
ments require  somewhat  complicated  special  apparatus  and 
a  special  training  in  manipulation,  and  the  methods  used 
and  the  results  obtained  may  be  stated  in  terms  that  make 
no  mention  of  mind.  Thus,  the  most  satisfactory  rate  for 
retention,  the  best  method  of  distributing  the  repetitions, 
the  rate  of  forgetting,  are  determined  by  objective  tests 
that  hold  irrespective  of  theory.  It  is  also  possible  to  study 
very  many  of  the  conditions  of  recall  by  objective  methods. 
One  may  speak  a  word  and  then  ask  the  observer  to  speak 
the  first  word  that  occurs  to  him.  A  study  of  the  connection 
between  these  words  permits  a  statement  in  a  perfectly 
objective  way  of  the  laws  that  hold  for  recall.  These  are 
the  facts  with  which  psychology  must  deal.  They  may  be 
collected  in  much  the  same  way  for  each  of  the  different 
activities  of  man. 

The  Nature  of  Psychology 

Methods  of  Psychology.  —  This  purely  objective  and 
experimental  study  of  mental  activities  depends  upon 
observation.  It  may  be  carried  on  for  man  in  exactly  the 
same  way  as  for  animals,  by  making  experiments  from  the 
outside,  with  no  attempt  to  discover  directly  what  has  been 
going  on  within  the  individual.  But  this  is  not  the  only 
method  of  psychology.  We  may  also  make  use  of  the 
individual's  report  on  the  processes.    He  can  observe  from 


INTRODUCTION  3 

within  what  accompanies  and  precedes  the  activities  objec- 
tively measured.  This,  the  process  of  self-observation  or 
introspection,  will  in  many  cases  supplement  the  results  of 
direct  observation,  and  the  individual  who  is  experimented 
upon  can  often  supply  an  explanation  when  the  observer  can 
find  none.  While  the  fundamental  causes  of  most  mental 
phenomena  are  as  much  hidden  from  him  as  from  the 
experimenter,  he  can  add  an  account  of  accompanying 
phenomena  that  is  nearly  always  suggestive,  and  may  at 
times  furnish  a  solution  for  the  questions  raised  by  the 
objective  results.  The  two  methods  of  psychology,  then, 
are  observation  and  introspection.  One  gives  the  phenom- 
ena as  they  present  themselves  to  the  onlooker,  the 
other  as  they  appear  to  the  individual  investigated.  At 
present  both  methods  are  used  under  experimental  condi- 
tions that  make  it  possible  to  control  the  stimuH  and  to 
provide  means  of  measuring  many  reactions  that  would 
escape  either  unaided  observation  or  introspection. 

The  Definition  of  Psychology.  —  While  practically  all 
are  agreed  as  to  the  field  which  psychology  is  to  study  and 
on  most  of  the  results  obtained,  there  is  and  always  has 
been  much  controversy  over  what  it  is  that  is  studied. 
Three  definitions  are  current  at  present  which  differ  in  the 
statement  of  the  object  to  be  studied : 

The  first  asserts  that  psychology  is  the  science  of 
mind,  a  direct  translation  of  the  original  Greek.  Two 
meanings  are  given  to  the  word  'mind.'  One  regards  it 
as  something  substantial,  an  actual  thing  or  an  actual 
force  which  produces  certain  effects  or  manifests  itself 
in  the  phenomena  we  directly  experience;  the  other, 
of  more  recent  development,  asserts  that  mind  is  just 
these  manifestations,  the  sum  of  mental  states  without 
any  assumption  as  to  what  it  is  that  produces  them. 


4  FUNDAMENTALS   OF   PSYCHOLOGY 

A  second  definition  makes  psychology  the  science  of 
consciousness.  Consciousness,  hke  mind  in  its  second 
definition,  is  just  the  series  of  mental  phenomena,  the 
memories,  thoughts  perceptions,  emotions  and  feeh'ngs 
as  they  are  immediately  experienced. 

A  third  definition,  most  recent  of  all,  defines  psy- 
chology as  the  science  of  behavior.     By  behavior  is 
meant  the  activity  of  the  man  or  animal  as  it  can  be 
observed   from   the   outside,   either   with   or  without 
attempting  to  determine  the  mental  states  by  inference 
from  these  acts. 
The   various   definitions   can   be   illustrated   concretely 
in  the  memory  process.     As  theory  of  mind,  psychology 
regards  memory  as  one  of  the  manifestations  of  mind  and 
either  is  concerned  with  understanding  mind  through  this 
manifestation  or  is  content  to  describe  remembering  as  one 
of  the  mental  capacities.     In  fact,  earlier  theories  of  mem- 
ory  were   content   to    assert   that   ideas   were    stored   in 
mind  or  that  they  were  impressions  made  upon  a  waxen 
plate.     In  either  case,  no  details  could  be  given  as  to  how 
they  were  stored  or  how  they  might  be  reinstated.     Mind 
was  both  an  active  agent  and  a  receptacle,  the  sole  means  of 
accounting  for  mental  states.     If  mind  is  to  be  defined  as  the 
sum-total  of  mental  states  in  accord  with  the  more  recent 
suggestions,  it  is  practically  synonymous  with  consciousness, 
—  the  first  definition  merges  into  the  second.     As  science  of 
consciousness,  psychology  is  concerned  with  a  description 
of  the  different  memory  images,  with  the  determination  of 
the  order  of  their  appearance  and  with  all  else  that  is  related 
to  their  structure  and  function.     It  takes  into  consideration 
nothing  that  is  not  to  be  discovered  by  the  individual  who 
remembers.     It  excludes  consideration  of  mind  as  a  store- 
house, for  that  is  not  open  to  observation;  and  also  of  mind 


INTRODUCTION  5 

as  a  wax  plate  or  other  similar  entity.  All  that  it  can  do 
is  to  determine  the  laws  of  succession  of  the  mental  states, 
and  to  describe  the  mental  states  themselves.  As  science  of 
behavior,  psychology  only  need  investigate  the  capacity  of 
the  individual  to  remember.  The  individual  is  asked  to 
repeat  words  or  syllables  a  certain  number  of  times  under 
dififerent  conditions.  After  a  certain  period  or  certain 
periods  he  is  tested  to  see  how  many  he  remembers.  From 
these  results  laws  can  be  formulated  for  the  most  effective 
means  of  learning. 

The  second  and  third  of  these  definitions  are  alike  in  that 
neither  imphes  any  theories  concerning  what  cannot  be 
seen,  what  is  not  open  to  observation.  Each  would  content 
itself  with  observation,  from  within  or  from  without,  of 
what  actually  takes  place.  As  in  all  sciences,  each  form  of 
observation  may  be  subjected  to  experiment,  the  condi- 
tions of  learning  may  be  varied  at  will,  the  corresponding 
changes  in  results  noted  and  formulated  in  laws.  The  choice 
between  them  must  be  made  in  terms  of  the  methods  that 
each  emphasizes,  and  on  the  basis  of  the  accuracy  with 
which  each  can  be  made  to  cover  the  facts  that  are  to  be 
included  under  psychology.  In  strict  definition,  all  is  at 
once  consciousness  and  behavior  for  most  individuals.  Few 
would  deny  that  all  behavior,  to  be  known,  must  become 
conscious,  either  to  the  actor  or  observer;  and  none  would 
deny  that  consciousness,  unless  it  is  to  remain  forever  indi- 
vidual, must  express  itself  in  behavior.  The  choice  of  the 
definition  'science  of  behavior'  turns,  first,  upon  the  fact 
that  consciousness  tends  to  imply  something  removed  from 
observation,  something  mystical,  a  thing,  rather  than  a 
series  of  phenomena;  secondly,  upon  the  fact  that  behavior 
is  the  more  inclusive  term;  and  finally,  upon  the  doubt 
expressed  by  recent  writers  as  to  whether  consciousness 


6  FUNDAMENTALS   OF   PSYCHOLOGY 

exists,  at  least  exists  for  them  individually.  It  emphasizes 
the  fact  that  laws  of  action  must  first  be  discovered,  and 
that  theories  and  theoretical  explanations  must  be  derived 
from  the  actual  results  of  experiment  and  observation, 
rather  than  be  accepted  in  advance. 

Behaviorism.  —  The  most  recent  development  in  method 
and  theory  has  grown  naturally  from  the  great  progress 
that  has  been  made  in  animal  psychology.  Experiments  on 
animals  are  of  necessity  limited  to  an  observation  of  what 
the  animal  does  under  rigidly  determined  conditions. 
(Some  of  the  earher  psychologists  made  inferences  from 
the  observed  movements  as  to  what  mental  processes  might 
accompany  them,  but  the  results  were  so  unsatisfactory 
that  all  assumptions  about  the  consciousness  of  animals 
were  abandoned.)  The  success  in  applying  the  method  of 
purely  objective  experimentation  to  animals  emphasized 
the  possibility  of  applying  the  same  method  to  man.  If 
one  could  develop  the  laws  of  man's  action  by  a  study  of  his 
responses  under  different  conditions,  it  would  not  be  neces- 
sary to  accept  the  unconfirmed  statements  of  the  observer, 
and  would  make  it  possible  to  check  each  observation  by 
several  individuals  or  to  record  them  graphically.  So  far 
as  it  can  be  apphed,  the  method  offers  obvious  advantages 
and  should  be  pushed  to  the  fullest  extent.  Whether  this 
can  be  the  only  method  in  psychology  is  still  a  matter  of 
debate.  Certain  of  the  questions  which  interest  the  psy- 
chologist concern  mental  states,  and  these  have  been  an- 
swered by  the  older  methods.  Up  to  the  present  time  no 
objective  investigations  of  these  problems  have  been  made, 
and  we  must  either  omit  them  or  state  the  results  of  the 
older  methods  on  the  older  presuppositions.  Watson,  the 
extreme  behaviorist,  relieves  himself  of  the  difficulty  by 
omitting  all  mention  of  mental  states,  and  by  asserting 


INTRODUCTION  7 

that  if  they  do  exist  they  cannot  be  made  the  basis  of 
a  science.  Many  of  his  more  moderate  followers  are  con- 
tent with  emphasizing  the  desirability  of  the  objective 
method  where  available.  Consciousness  seems  to  them  a 
fact  of  immediate  experience.  If  it  exists  it  should  be  taken 
into  account  in  a  study  of  behavior,  when  it  contributes 
relative  data.  All  psychologists,  of  whatever  school,  will 
hail  with  delight  the  fullest  application  of  the  objective 
methods;  the  behaviorists  that  it  may  supplant,  others 
that  it  may  supplement,  introspection. 

The  three  definitions  do  not  differ  essentially  as  to  what 
the  phenomena  of  consciousness  are,  nor  as  to  the  general 
laws  that  express  them,  but  rather  in  the  theoretical  expla- 
nations which  each  offers.  Thus  the  exponent  of  the  extreme 
behaviorist  view  differs  from  the  extreme  subjectivist  not 
in  the  facts  he  accepts  but  in  that  he  does  not  believe  that 
consciousness  exists,  or  if  it  exists,  that  it  plays  any  impor- 
tant part  in  controlling  action.  For  the  subjectivist,  on  the 
other  hand,  consciousness  seems  the  final  term  by  which 
all  else  must  be  explained;  behavior  is  secondary.  In  the 
first  definition,  the  use  of  mind  is  very  obviously  the  intro- 
duction of  a  theoretical  explanation.  No  one  claims  that  it 
is  ever  open  to  direct  observation,  however  important  it 
may  appear  to  the  individuals  who  believe  in  it.  These 
differences  of  opinion  on  theoretical  points  may  very  well 
be  neglected  in  the  development  of  a  description  of  the 
mental  life.  After  facts  have  been  collected  and  laws  for- 
mulated, the  fundamental  problems  may  be  attacked  in 
the  Kght  of  those  results.  Laws  are  bound  to  suggest  wider 
generalizations,  and  these  in  turn  reveal  fundamental  causes 
or  conditions. 

Psychology  Treats  Only  Certain  Phases  of  Behavior.  — 
Obviously,  if  we  are  to  define  psychology  as  the  science  of 


8  FUNDAMENTALS   OF   PSYCHOLOGY 

behavior,  we  must  limit  its  application,  since  all  of  the 
biological  and  even  the  chemical  and  physical  sciences  are 
needed  to  explain  behavior  in  its  completeness.  In  practice, 
we  Hmit  ourselves  to  the  explanation  of  intelligent  behavior. 
Roughly,  behavior  may  be  regarded  as  inteUigent  when  it 
is  modified  by  the  earlier  experience  of  the  organism.  All 
the  acts  of  certain  of  the  lowest  organisms  and  some  of  the 
acts  of  the  highest  are  to  be  explained  altogether  in  terms 
of  the  physical  stimuH  and  of  the  constitution  of  the  organ- 
ism. In  consequence,  these  responses  are  relatively  invaria- 
ble, —  the  organism  makes  the  same  movements  under 
the  same  conditions;  such  responses  do  not  concern  psy- 
chology. When  behavior  is  modified,  not  merely  by  the 
physical  stimuli  and  chance  chemical  conditions  of  the 
organism,  but  also  by  the  results  of  earlier  behavior,  we 
have  the  first  beginnings  of  intelHgence,  and  the  organism 
offers  material  for  psychology.  Even  in  the  highest  organ- 
isms, psychology  is  concerned  only  with  the  phases  of  be- 
havior which  cannot  be  referred  directly  to  chemical  and 
physical  changes  within  and  without  the  organism.  It 
deals  in  general  with  the  acts  of  the  organism  as  a  whole, 
rather  than  of  the  parts,  and  it  considers  the  acts  of  the 
organism  only  in  so  far  as  they  are  not  explained  by  physi- 
ology and  other  distinctly  biological  sciences.  In  general, 
again,  psychology  treats  behavior  in  so  far  as  it  is  deter- 
mined by  previous  acts  of  the  individual,  by  other  more 
remote  influences,  while  the  other  sciences  treat  the  same 
behavior  in  so  far  as  it  is  due  to  the  activities  of  particular 
organs  and  to  the  more  mechanical  forces. 

The  Scope  of  Psychology 

Psychology  in  its  Relation  to  Other  Sciences.  —  If  part 
of  all  behavior  is  to  be  explained  by  other  sciences,  by 


INTRODUCTION  9 

physiology,  by  anatomy,  and  the  other  biological  sciences, 
the  psychologist  must  take  the  results  of  these  sciences  into 
consideration.  He  must  know  what  part  of  the  problem 
they  solve  and  what  they  leave  over  for  him  to  discuss.  He 
must  also  use  many  of  their  results  in  attaining  his  own  con- 
clusions. Knowledge  of  the  structure  and  function  of  the 
nervous  system  is  particularly  important,  as  in  the  higher 
organisms  practically  all  behavior  is  an  expression  of 
nervous  action.  Capacity  for  the  more  complex  forms  of 
behavior  develops  with  the  nervous  system,  and  defects  in 
the  nervous  system  are  closely  correlated  with  deviations 
from  normal  behavior.  Consciousness,  too,  is  closely  related 
to  the  nervous  system.  One  can  become  aware  of  external 
objects  only  as  stimuli  are  carried  to  the  brain  by  the  sensory 
nerves;  memory  defects  accompany  injuries  to  definite 
portions  of  the  brain  tissue.  In  fact,  we  have  every  reason 
to  believe  that  all  forms  of  consciousness  have  definite 
accompaniments  in  the  nervous  system.  Viewed  from  any 
standpoint,  the  problems  of  psychology  are  closely  bound 
up  with  the  problems  of  the  nervous  system.  A  knowledge 
of  nervous  anatomy  and  physiology  is  essential  to  an  under- 
standing of  either  consciousness  or  behavior.  We  shall 
begin  our  work  with  a  brief  survey  of  the  more  important 
facts  of  neurology.  This  survey,  it  may  be  well  to  state,  is 
not  part  of  the  field  of  psychology.  It  is  given  here  only 
because  one  cannot  presuppose  that  all  readers  have  a 
knowledge  of  the  nervous  system,  and  acquaintance  with 
the  facts  is  necessary  to  an  understanding  of  many  defi- 
nitely psychological  problems.  A  full  preparation  for  com- 
mencing the  study  of  psychology  makes  requisite  also  the 
results  of  physics  and  chemistry.  All  of  the  activities  of 
the  organism  involve  chemical  processes,  and  the  stimuli 
to  action  are  physical.    In  brief,  all  of  the  sciences  deaHng 


lo  FUNDAMENTALS   OF   PSYCHOLOGY 

with  any  of  the  forces  that  arouse  or  modify  action  and  with 
the  nature  of  the  organism  itself  must  be  of  assistance  to 
psychology. 

In  addition  to  the  sciences  to  which  psychology  must  look 
for  aid  in  solving  its  problems,  it  also  has  close  relations 
with  many  of  the  social  sciences,  which  either  depend  upon 
it  or  share  with  it  in  the  solution  of  their  own  problems. 
Sociology  in  its  attempt  to  understand  society  must  take 
into  consideration  the  individuals  of  which  it  is  composed, 
and  welcomes  whatever  light  psychology  can  shed  on  the 
subject.  In  many  of  its  phases  sociology  is  social  psychology. 
Similarly,  much  of  the  work  in  economics  depends  upon  a 
knowledge  of  mental  laws.  The  economist,  however,  has 
for  the  most  part  developed  his  laws  of  human  nature  for 
himself  from  a  study  of  practical  relationships,  rather  than 
from  the  findings  of  psychology.  The  relationship  of  psy- 
chology to  philosophy  is,  for  the  theoretical  problems, 
closest  of  all.  Psychology  was  the  latest  of  the  sciences  to 
separate  from  philosophy,  and  the  attitude  toward  many 
of  the  fundamental  problems  is  still  profoundly  influenced 
by  philosophical  considerations.  Each  of  the  definitions  of 
psychology  discussed  has  developed  in  response  to  philo- 
sophical theories.  On  the  other  hand,  many  of  the  philo- 
sophical discussions  presuppose  a  knowledge  of  psychology. 
There  has  always  been  an  interaction  between  the  two 
disciplines. 

Subdivisions  of  Psychology 

The  Varieties  of  Psychology.  —  The  more  usual  classifi- 
cations of  psychology  have  been  based  upon  the  ways  of 
approaching  the  subject,  upon  the  methods  used  in  the 
investigation,  or  upon  the  field  that  is  treated.  The  older 
psychologies  were  divided  into  rational  or  deductive,  and 


INTRODUCTION  ii 

empirical  or  inductive  (on  the  basis  of  the  fundamental 
method  employed).  Recently  all  psychology  has  tended  to 
become  empirical  or  inductive,  particularly  with  the  in- 
creased use  of  experiment;  and  the  method  of  deduction 
has  been  apphed  only  to  topics  that  do  not  lend  themselves 
to  experiment  or  observation.  Rational  psychology  as  a 
separate  field  has  largely  disappeared.  Even  Wolff,  who 
may  be  said  to  have  introduced  and  certainly  to  have  made 
large  use  of  the  distinction,  was  not  able  to  keep  the  two 
apart;  but  was  continually  turning  from  one  to  the  other. 
Two  branches  have  received  names  from  the  direction  of 
approach:  physiological  psychology  and  psychophysics. 
The  former  treats  of  the  mental  processes  in  their  relation 
to  the  nervous  system  and  its  action.  It  is  impHed  in  all 
forms  of  psychology  at  the  present  time  and  differs  from  the 
others  for  the  most  part  only  in  the  relative  amount  of  space 
devoted  to  the  physiological  aspects.  All  psychologists  at 
present  presuppose  a  knowledge  of  the  nervous  system  and 
its  action,  even  if  they  do  not  discuss  it  explicitly.  Much 
the  same  may  be  said  of  psychophysics.  This  lays  greatest 
emphasis  upon  the  part  the  physical  stimuli  play  in 
mental  processes,  and  the  way  in  which  mental  states 
change  with  changes  in  physical  stimuli.  Both  physiologi- 
cal psychology  and  psychophysics  were  titles  of  important 
works  on  psychology,  the  one  by  Wundt,  the  other  by 
Fechner.  Closely  connected  with  physiological  psychology 
is  objective  psychology,  a  name  given  to  several  recent 
books.  This  not  merely  places  the  emphasis  upon  the 
nervous  system  and  its  activity,  but  actually  leaves  con- 
sciousness out  of  consideration  altogether.  It,  like  be- 
haviorism, studies  behavior  from  the  outside  only. 

Different  Fields  of   Psychology.  —  Psychology  may  be 
divided  with  reference  to  subject  matter.    Most  psychology 


12  FUNDAMENTALS   OF   PSYCHOLOGY 

deals  with  the  adult  human  individual,  but  recently  many 
additional  and  special  fields  have  been  developed. 

Social  Psychology. —  Society,  or  man  in  the  mass,  may  be 
studied,  as  well  as  the  individual.  A  society  shows  many 
characteristics  different  from  and  in  addition  to  the  qualities 
of  the  individual.  A  mob,  for  example,  will  do  many  things 
that  few  if  any  of  the  individuals  who  compose  the  mob 
would  countenance  in  calm  moments.  These  and  other 
phases  of  group  psychology  have  been  studied,  and  a  series 
of  important  laws  developed.  Race  psychology  deals  with 
the  broader  mental  differences  between  races  and  is  a 
natural  extension  of  social  psychology  but  has  been  less 
fully  developed. 

Genetic  Psychology.  —  A  second  group  of  divisions  of 
psychology,  genetic  psychology,  treats  the  less  developed 
types,  either  with  the  object  of  throwing  Hght  upon  more 
complex  human  behavior  or  for  their  own  sake.  The  most 
fully  developed  of  these  is  animal  psychology.  The  question 
as  to  whether  or  not  animals  are  intelHgent  and  how  their 
intelUgence  compares  with  man's  has  always  interested 
students,  but  until  within  the  last  two  decades  most  of  the 
conclusions  were  based  upon  anecdotes  or,  at  most,  upon 
the  chance  observations  of  travellers  and  naturahsts.  These 
were  obviously  not  trustworthy.  More  recently,  experi- 
ments upon  animals  have  been  carried  on  by  both  biologists 
and  psychologists,  with  very  important  results.  The  be- 
havior of  typical  animals  from  the  protozoa  to  the  apes 
has  been  studied  exhaustively.  Much  hght  has  been  thrown 
upon  their  own  activities,  and  many  points  in  human  psy- 
chology have  also  been  illuminated  by  these  results.  The 
development  of  the  individual  has  also  been  investigated. 
Child  study  has  offered  a  number  of  conclusions  that  make 
easier  an  understanding  of  the  compHcated  activities  of 


INTRODUCTION  13 

man.    The  earliest  years  and  the  period  of  adolescence  have 
received  most  attention. 

Abnormal  Psychology.  —  Still  another  important  series 
of  problems  has  arisen  in  connection  with  different  forms  of 
mental  deterioration,  the  psychology  of  the  abnormal,  or 
pathological  psychology.  The  relation  of  these  studies  to 
normal  psychology  has  been  twofold.  They  have  greatly 
aided  in  an  understanding  of  the  normal  individual.  One 
is  very  much  more  certain  that  a  voluntary  act  depends 
upon  certain  stimuli  or  sensations  when  it  can  be  shown  that 
the  absence  of  that  stimulus  causes  a  defect  in  the  move- 
ment. Disturbances  of  the  self  have  given  a  more  profound 
knowledge  of  what  the  self  is  or  is  not  than  centuries  of 
speculation  and  introspection.  Slighter  defects  of  sensa- 
tion, color  blindness  and  partial  deafness,  not  to  mention 
the  impairment  of  memory  and  related  processes,  have  all 
given  valuable  aid  in  the  unravelKng  of  psychological  prob- 
lems, or  have  substantiated  results  obtained  in  other  ways. 
On  the  other  hand,  psychological  methods  and  psychological 
results  have  been  adapted  to  the  study  of  the  abnormal  and 
defective  minds  with  much  theoretical  and  practical  benefit. 
Certain  standardized  tests  have  come  into  use  which  make 
it  possible  to  determine  within  fairly  close  hmits  the  degree 
of  intelhgence  of  the  individual.  These  have  proved  of  value 
in  the  schools  in  selecting  the  children  who  are  unable  to 
profit  from  the  usual  training,  and  make  it  possible  to  give 
them  special  instruction.  It  has  been  shown  by  an  exami- 
nation of  criminals  and  paupers  that,  in  a  large  number  of 
cases,  a  mental  defect  is  responsible  for  their  failure  to  fit 
into  society;  and  the  necessity  for  special  care  that  shall 
provide  the  ounce  of  prevention  has  been  emphasized. 
Many  of  the  methods  used  to-day  for  the  diagnosis  of 
insanity  have  also  been  developed  in  psychological  labora- 


14  FUNDAMENTALS   OF   PSYCHOLOGY 

tories,  and  much  of  the  treatment  has  been  an  outgrowth 
of  psychological  principles,  an  application  of  psychological 
methods. 

Our  Problem.  —  In  this  work  we  shall  restrict  ourselves 
to  a  study  of  the  normal  adult  human  individual.  Reference 
will  be  made  to  the  other  branches  of  psychology  only  in 
so  far  as  their  results  aid  us  in  understanding  this  central 
problem;  they  render  valuable  aid  at  practically  every 
point.  We  shall  use  the  results  of  all  methods,  but  shall 
enter  as  Kttle  as  possible  into  the  controversies  as  to  whether 
any  one  method  is  theoretically  justifiable.  We  shall  assume 
that  there  is  a  body  of  fact  that  is  independent  of  the 
theoretical  discussions.  Thus,  in  connection  with  the  dif- 
ference of  opinion  as  to  whether  observation  or  introspec- 
tion is  the  method  in  psychology,  we  shall  remain  neutral, 
and  make  use  of  the  contributions  of  each  method.  After 
all,  the  controversy  concerns  us  only  in  its  effect  upon  the 
form  of  expression  that  may  be  used  to  state  the  results 
rather  than  in  the  vahdity  of  the  results  themselves.  Most 
of  these  results  may  be  expressed  equally  well  in  terms  of 
one  theory  or  the  other,  and  where  they  cannot  we  shall 
use  the  terminology  best  suited  to  the  particular  statements 
in  hand.  The  facts  are  important  and  will  persist,  while 
the  theories  that  interpret  them  are  in  constant  flux.  We 
shall  be  concerned  primarily  with  facts,  and  the  theories 
will  be  considered  only  where  they  serve  to  make  clear  the 

facts. 

REFERENCES 

Angell:  Chapters  in  Modern  Psychology. 

Watson:  Psychology   from   the   Standpoint   of   a  Behaviorist, 

Ch.  I. 
Bertrand  Russell:  The  Analysis  of  Mind. 
Warren:  Human  Psychology,  Ch.  I. 
Wood  worth:  Psychology,  Ch.  I. 


CHAPTER  II 

THE  NERVOUS  SYSTEM 

Broadly  speaking,  the  physical  basis  of  mind  is  to  be 
found  in  the  nervous  system.  In  a  very  general  sense,  the 
nervous  system  is  the  organ  of  mind.  When,  however,  we 
approach  it  from  the  physical  side,  it  is  also  the  organ  which 
makes  possible  the  activities  of  the  body,  which  permits 
external  stimuH  to  act  upon  the  muscles,  and  coordinates 
the  different  movements  so  that  they  may  bring  about  har- 
monious and  unified  action.  An  understanding  of  the  action 
and  even  of  the  structure  of  the  nervous  system  is  very 
much  easier  if  we  keep  the  emphasis  upon  the  relation  of 
the  nervous  system  to  bodily  movement  —  treat  it  first  for 
itself  —  than  if  we  think  of  it  in  its  relation  to  consciousness. 
The  problem  of  the  relation  of  body  and  mind  may  be 
taken  up  when  we  know  more  of  body.  The  nervous  system 
in  vertebrates  is  made  up  of  the  brain  and  spinal  cord  with 
the  sensory  and  motor  nerves  that  extend  from  these  cen- 
tral organs  to  the  sense  organs  and  muscles.  The  brain  fills 
the  upper  part  of  the  skull,  while  the  spinal  cord  is  found  in 
the  spinal  column.  The  details  of  the  structures  can  be 
understood  more  readily  if  we  consider  them  later  in  con- 
nection with  their  development  in  the  race  and  in  the 
individual. 

Behavior  of  Lower  Organisms 
Life  Processes  in  Cells.  —  It  is  much  easier  to  understand 
the  action  of  higher  animals  and  the  nervous  structures 


1 6  FUNDAMENTALS   OF   PSYCHOLOGY 

themselves  if  we  commence  by  describing  briefly  the  animal 
organisms  which  do  not  possess  nerve  tissue,  the  so-called 
unicellular  organisms.  This  is  the  type  of  organism  from 
which  all  the  higher  forms  are  assumed  to  have  developed. 
Of  the  single-celled  animals,  or  protozoa,  one  that  is  most 


Fig.  I.  —  Amoeba  chasing  and  attempting  to  ingest  a  euglena.   (From  Jennings.) 

frequently  used  to  illustrate  the  type  is  the  amoeba.  It  is 
merely  a  drop  of  Kquid  of  unknown  but  highly  complex 
chemical  composition  contained  in  a  dehcate  semipermeable 
membrane.  Since  this  is  the  original  tissue  from  which  all 
other  Hving  matter  is  developed,  it  is  known  as  protoplasm. 
We  know  that  protoplasm  is  made  up  of  highly  unstable 
chemical  compounds,  mostly  hydrocarbons,  but  the  differ- 
ent   components    have    never    been    completely    isolated 


THE  ACTIVITIES   OF   PROTOZOA  17 

or  analyzed.  Whatever  the  composition  of  this  chemical 
substance,  it  is  constantly  undergoing  change.  It  takes  to 
itself  other  organic  compounds  and  oxygen  and  gives  off 
carbonic  acid.  It  is  constantly  taking  something  from  the 
medium  in  which  it  Uves  and  giving  off  waste  products. 
Both  of  these  changes  take  place  through  the  semipermeable 
membrane  by  a  process  which  the  physicist  calls  osmosis. 
Within  the  body  of  the  cell  is  a  darker  spot,  known  as  the 
nucleus.  This  nucleus  is  closely  connected  with  the  nutri- 
tive processes  and  the  subdivision  of  the  cell.  Much  still 
remains  to  be  known  of  the  life  processes  in  the  cell.  We 
can  only  give  the  briefest  account  of  what  is  known  —  that 
some  chemical  processes  must  go  on  within  the  cell,  that 
the  materials  involved  are  admitted  to  the  cell  by  osmosis 
through  the  membrane,  and  that  these  processes  taken  to- 
gether make  possible,  if  they  do  not  constitute,  what  we 
call  life. 

The  Activities  of  Protozoa.  —  If  we  study  the  activities 
of  one  of  the  unicellular  organisms,  we  find  that  in  a  simple 
way  it  can  do  almost  everything  that  the  most  highly 
organized  animal  can,  and  that  it  follows  the  same  funda- 
mental laws  of  behavior.  It  takes  nourishment,  it  breathes, 
and,  what  is  most  important  from  our  point  of  view,  it 
moves  upon  stimulation  of  any  part.  If  particles  of  a  cer- 
tain chemical  composition  come  into  contact  with  its 
membrane,  it  enfolds  them,  and  the  process  of  digestion 
through  the  membrane  of  the  cell  begins.  If  other  particles 
of  another  kind  come  into  contact  with  it,  it  moves  quickly 
away.  When  in  contact  with  a  sohd  body,  it  may  send  out 
a  prolongation  of  its  body  in  the  form  of  a  foot  or  what  is 
known  as  a  pseudopod  (false  foot)  which  attaches  itself 
to  the  surface,  and  the  whole  body  then  draws  itself  up  to 
the  foot,  which  is  then  withdrawn  into  the  rest  of  the  body. 


i8 


FUNDAMENTALS   OF   PSYCHOLOGY 


m^^ 


The  single  cell  is  stomach,  lung,  and  organ  of  locomotion,  in 
one. 

Study  of  the  responses  of  the  amoeba  and  of  the  stimuH  to 
which  it  responds  shows  its  similarity  to  the  higher  organ- 
^^,^r==r:=^  isms.       When    stimulated 

.^^W^"""^  gently  by  a  solid  surface, 

,•  '";  ;^"f  :  its  activity  is  not  changed, 

,;^  :;  -V       •  but,    if    the   excitation   is 

S^S  V  S  ■■  stronger,  it  at  once  stops 

''^''i^:'i^^i^'J'-'-  3-11  movement  and  rolls  up 

into  a  ball.  If  the  stimu- 
lation is  continued,  it  may 
send  out  a  pseudopod  on 
the  opposite  side  and  roll 
away  from  the  stimulus. 
In  these  two  ways  the 
protozoa  respond  to  Ught, 
heat,  the  motion  of  the 
liquid  medium,  the  attrac- 
tion of  gravitation,  and  to 
the  presence  of  chemicals 
in  the  Kquid.  In  general, 
beneficial  stimuK  have  no 
effect,  while  harmful  stim- 
uK cause  k  movement  that 
removes  the  organism  from 
its  neighborhood.  Certain  organisms,  the  Stentor  that  Jen- 
nings worked  with,  for  example,  modify  their  reactions  in 
accordance  with  the  result  of  earlier  reactions,  and  thus 
give  the  first  evidence  of  learning.  If  we  use  variability  of 
response  as  a  mark  of  intelligence,  this  may  be  regarded  as 
an  intelligent  act.  The  first  response  of  the  Stentor  when 
stimulated  is  to  withdraw  into  its  tube.     After  this  has 


Fig.  2.  —  Stentor   stimulated   by   carmine 
particles.      (From  Jennings.) 


MAN  A   COLONY  OF   CELLS  19 

been  repeated  several  times,  it  changes  its  form  of  response 
to  bending  to  one  side  to  escape  the  contact.  Later  it  may, 
when  strongly  and  repeatedly  stimulated,  loosen  its  hold 
on  the  tube  and  swim  away.  These  latter  responses  were 
called  out  by  permitting  water  mixed  with  carmine  parti- 
cles to  reach  its  disk. 

Each  of  these  responses  is  to  be  thought  of  as  the  result 
of  the  transfer  of  a  chemical  stimulus  from  the  point  of 
stimulation  to  a  more  or  less  remote  portion  of  the  cell 
where  the  movement  is  made.  Did  we  know  the  exact 
nature  of  the  processes  in  these  simplest  cells,  many  of  the 
problems  of  man 's  action  would  be  solved.  So  far  we  have 
only  commenced  in  that  direction,  although  advances  are 
being  made  frequently.  At  the  present  stage  of  our  knowl- 
edge we  can  do  no  more  than  express  the  behef  that  a 
chemical  or  physical  explanation  may  some  day  be  found. 
Meanwhile  we  may  use  the  action  of  these  simple  organ- 
isms as  a  type  of  the  action  of  cells  in  general. 

The  Nerve  Cells  in  Man 

Man  a  Colony  of  Cells.  —  These  responses  are  important 
for  us  from  the  fact  that  one  may  think  of  all  of  the  higher 
organisms  as  compounded  of  cells  like  these  simple  unicel- 
lular organisms,  wliich  have  undergone  various  modifica- 
tions as  a  result  of  living  together  in  a  colony,  but  still  re- 
tain many  of  the  characteristics  of  the  original  free-swim- 
ming protozoa.  For  our  present  purposes,  the  body  of 
man  may  be  pictured  as  a  mass  of  cells  in  which  each  class 
has  developed  speciahzations  that  fit  it  to  fulfil  some  one 
function.  With  increased  capacity  for  this  function,  others 
of  the  primitive  capabiUties  have  been  lost.  Nevertheless 
the  rudiments  of  all  the  capacities  of  the  complex  organ- 
isms are  to  be  found  in  the  unicellular  organisms.    In  the 


FUNDAMENTALS   OF   PSYCHOLOGY 


body,  the  nerve  cells  are  among  the  least  modified.  Unlike 
the  bone  cells,  for  example,  that  become  so  filled  with  salts 
as  to  retain  but  shght  similarity  to  the  original,  the  nerve 
cells  lack  motion  alone  of  the  capacities  of  the  prototype. 
Only  certain  of  the  blood  corpuscles  retain  more  of  the 
original  properties;  the  leucocytes,  or  white  blood  corpus- 


FiG.  3.  —  A  group  of  human  nerve-cells  drawn  to  the  same  scale,  a,  small  cell 
from  the  ventral  horn  of  the  cord;  b,  cell  from  Clarke's  column;  c,  small  nerve-cell 
from  tip  of  dorsal  horn,  thoracic  cord;  d,  spinal  ganglion  cell,  cervical  root;  e,  three 
granules  from  cerebellum;  /,  Purkinje  cell  from  cerebellum;  g,  small  pyramidal  cell 
from  second  layer  of  central  gyri  of  cortex;  ft,  giant  pyramidal  cell  from  same 
region.    (From  Donaldson,  after  Adolf  Meyer.) 

cles,  seem  to  five  almost  as  independent  an  existence  in  the 
blood  as  the  amoeba  in  its  watery  mediuni. 

Morphology  of  Neurones.  —  The  cells  of  the  nervous 
system  have  retained  especially  the  sensitivity  and  con- 
ductivity of  the  unicellular  forms.  In  brief,  the  elements 
of  the  nervous  system,  known  as  neurones  (also  spelled 
neurons),  consist  of  a  central  cell,  the  representative  of 
the  cell  body,  and  numerous  processes  that  extend  in  all 
directions  from  that  cell  body.  The  cell  body  is  of  a  more 
or  less  irregular  shape  and  varies  in  diameter  from  about 


MORPHOLOGY  OF  NEURONES  21 

2Fff  to  TO  of  a  millimetre.  The  shapes  can  be  seen  from  the 
accompanying  diagrams.  Within  the  body  of  the  cell  arc 
found  a  nucleus  and  a  nucleolus,  as  in  all  cells.    Within  the 


Fig.  4.  —  Cells  from  the  cord  of  a  rabbit,  showing  internal  structures.  A,  B,  C, 
motor  cells;  D,  small  cell  from  the  spinal  root;  a,  bundles  of  neurofibrils;  c,  perinu- 
clear plexus;  d,  the  empty  areas  correspond  to  the  Nissl  bodies;  e,  section  of  a  den- 
drite, showing  similarity  to  cell  tissue.    (From  Cajal.) 

protoplasm  are  small  particles  that  stain  easily,  named 
Nissl  or  tigroid  bodies,  the  former  after  their  discoverer. 
In  many  cells  can  also  be  seen  fine  fibrils  that  run  through 
the  bodies  of  the  cells  and  into  the  processes.    It  is  not  pos- 


2  2  FUNDAMENTALS   OF   PSYCHOLOGY 

sible,  however,  to  assert  positively  what  function  these  dif- 
ferent parts  of  the  cell  have.  The  nucleus  and  Nissl  bodies 
are  probably  closely  connected  with  the  nutrition  of  the 
cell.  Some  theories  assign  a  highly  important  function  to 
the  fibrils,  but  the  balance  of  opinion  seems  opposed  to  re- 
garding any  one  part  of  the  cell  as  the  fundamental  seat  of 
its  activity.  We  cannot  as  yet  analyze  the  action  of  the 
cell  into  elements,  but  must  think  of  it  as  acting  as  a  unit. 
Axones  and  Dendrites.  —  The  processes  or  extensions  of 
the  neurones  are  of  two  sorts,  distinguished  rather  by  func- 
tion than  by  structure.  One,  which  serves  to  conduct  im- 
pressions away  from  the  cell  body,  is  usually  long,  with 
relatively  few  branches,  and  these  at  right  angles  to  the 
main  stem.  It  is  called  the  axone  (also  spelled  axon).  The 
axone  terminates  in  the  end  brush,  a 
number  of  short  branches,  each  of 
which  is  probably  continuous  with  a 
*  fibril  in  the  axone.    The  other  is  usually 

made  up  of  a  number  of  fibres  much 
shorter  and  much  branched,  is  in  fact 
usually  a  thick  network  like  the  roots 
of  a  tree,  an  appearance  that  gives  the 
--Nucleus        ^j^Qig  j^g   ^^^^^   ^j^g  dendrite.     This 

usually  carries  impressions  to  the  cell 
Fig.    s.  —  'T'- shaped    body.    The  axones  may  be  of  consider- 
ed! from  spinal  ganglion   ^^1^  length.     A  single  axone  extends 

of    frog.      (irom   Boehm-  "  ° 

Davidoff- Ruber's  "His-  from  the  brain  to  the  lower  cord  in 
'°  °^^'  the  case  of  the  motor  fibres  and  sensory 

axones  from  the  cord  to  the  medulla.  The  axones  carry 
impulses  away  from  the  cells.  The  dendrites  are  nearly 
always  relatively  short,  less  than  a  milHmetre  in  length. 
The  one  striking  exception  is  found  in  the  case  of  the 
dendrites  of  the  sensory  neurones  whose  cells  are  found 


THE  SHEATHS  OF  THE  AXONES     23 

in  the  spinal  ganglia,  masses  of  nerve  tissue  near  the 
cord.  They  serve  to  transfer  impressions  from  the  organs 
of  the  skin  and  lower  body  to  the  cord  and  brain.  The 
process  that  runs  to  the  skin  may  be  two  feet  or  more 
in  length,  extending  from  the  skin  of  the  toe,  for  example, 
to  the  T-shaped  cell  body  in  a  spinal  ganghon  in  the  lower 
part  of  the  back.  In  appearance  it  is  not  to  be  distin- 
guished from  the  fibre  of  an  axone,  but  its  function  is  to 
carry  an  impulse  to  the  cell,  the  function  of  a  dendrite.  It 
is  sometimes  called  a  teledendrion,  or  long  dendrite,  to 
avoid  the  difficulty  of  classing  it  either  with  the  axone  or 
with  the  dendrite. 

The  Sheaths  of  the  Axones.  —  The  axones  do  not  show 
a  homogeneous  cross  section,  but  consist  of  several  parts. 
In  the  centre  is  a  core  of  protoplasm  continuous  with  the 
structure  of  the  cell  body.  In  it  may  be  traced  the  minute 
fibrils  that  were  mentioned  above  as  found  in  the  cell. 
About  this  central  core  of  nervous  tissue  are  found  one  or 
two  coverings  or  sheaths.  One,  the  outer,  known  as  the 
neurilemma,  or  sheath  of  Schwann,  is  a  thin  white  layer, 
segmented  or  notched  at  intervals.  Many  fibres  have 
within  this  outer  sheath  a  thicker  coating  of  fatty  sub- 
stance known  as  the  medullary  or  myehn  sheath.  This  is 
absent  in  the  nerves  of  the  sympathetic  system  and  at  the 
early  stages  of  the  development  of  the  fibres  in  the  brain. 
The  neurilemma  is  found  on  the  peripheral  nerves,  but  is 
lacking  within  the  central  nervous  system.  The  axone 
lacks  both  sheaths,  too,  for  a  short  distance  after  it  leaves 
the  cell  body  and  the  end  brush  is  also  always  bare.  Flech- 
sig  has  inferred  that  the  medullary  sheath  is  necessary  for 
the  action  of  brain  fibres  from  the  fact  that  this  sheath  de- 
velops successively  on  different  groups  of  fibres,  as  the  in- 
dividual grows  older  before  and  after  birth,  and  that  fibres 


24  FUNDAMENTALS   OF   PSYCHOLOGY 

continue  to  be  meduUated  up  to  and  beyond  middle  age. 
The  facts  that  some  fibres  are  always  without  this  sheath 
and  that  animals  can  learn  before  their  cerebral  fibres  are 
medullated  make  its  importance  somewhat  doubtful.  The 
central  core,  then,  may  be  regarded  as  the  path  of  the  im- 
pulse, and  the  sheaths  as  largely  protective.  In  a  periph- 
eral nerve  several  thousands  of  these  fibres  may  be 
united.  In  the  optic  nerve  it  is  estimated  that  there  are 
100,000  of  them  grouped  together.     Between  the  nerve 


O 


Fig.  6.  —  LongitudiBal  and  transverse  sections  of  a  medullated  nerve  fibre.  The 
myelin  sheath  is  shown  in  black;  the  central  protoplasm  shows  its  fibrous  structure. 
(From  Barker,  after  Biedermami.) 

cells  are  numerous  cells  of  a  different  character,  the  neu- 
roglia cells.  They  are  supposed  to  have  no  part  in  the  con- 
ductivity of  the  nervous  system,  but  to  constitute  support- 
ing structures.  Their  exact  function  is  not  known.  Their 
shapes  may  be  seen  in  Figure  7. 

The  General  Plan  of  the  Nervous  System 

The  General  Outlines  of  the  Nervous  System.  —  The 
nervous  system  of  man  is  altogether  made  up  of  these  neu- 
rones held  together  by  their  own  cohesion  and  the  pres- 
sure of  the  bones  and  other  surrounding  tissues.  The  pe- 
culiarities of  appearance  of  the  different  structures  are  due 
to  the  way  in  which  the  different  elements  are  combined  to 


GENERAL  OUTLINES  OF  NERVOUS  SYSTEM     25 

constitute  the  masses.  As  one  looks  at  the  nervous  system 
of  a  mammal,  one  may  distinguish  three  parts.  The  largest 
is  the  cerebrum,  which  fills  the  upper  portion  of  the  skull, 
next  below  is  the  brain  stem,  so  called  because  it  may  be 
regarded  as  supporting  the  brain  proper.  The  largest  part 
of  this  is  the  cerebellum,  which  lies  in  man  just  below  the 
cerebrum,  although  it  is  attached 
to  the  brain  stem  below  several 
of  the  other  important  structures. 
In  the  brain  stem  between  the 
base  of  the  cerebrum  and  the 
point  of  attachment  of  the  cere- 
bellum are  the  corpora  quadri- 
gemina  and  the  thalami.  The 
latter  are  at  the  base  of  the  cere- 
brum, the  former  just  below  it.  Fig.  7.  — Neuroglia  cell.  In 
,T,,       ,  ,  ,  n      -  .•  this  preparation  the  cell  is  promi- 

The  lowest    and    smallest    portion    ^ent.     in  the  more  usual  method 
of  the  brain  stem  is    the  medulla,    of  staining    the   fibres  are    more 

stnkmg    and    give    the    so-called 
Just  below  that  is  the  spinal  cord,     spider  cells.      (From  Huber,  after 

the  third  of  our  main  divisions,  "^ 
which  extends  about  two-thirds  the  length  of  the  spinal 
column.  The  position  of  these  more  prominent  organs 
should  be  carefully  studied  in  Figure  8.  Superficially  re- 
garded, the  most  striking  differences  between  different 
structures  are  in  the  colors.  The  cortex,  or  outer  layer  of 
both  cerebrum  and  cerebellum,  is  gray;  the  cord  is  white. 
The  gray  color  is  given  by  masses  of  cell  bodies  closely 
crowded  together,  while  the  white  color  is  given  by  the 
white  sheaths  of  the  nerve  fibres.  Similarly,  a  section 
through  any  part  of  the  central  nervous  system  will  show 
masses  of  white  matter  and  other  masses  of  gray  matter. 
In  the  cord  the  centre  is  gray,  the  outer  parts  white;  in 
the  cerebrum  the  relation  is  reversed,  but  in  each  case  the 


26 


FUNDAMENTALS   OF   PSYCHOLOGY 


Fig.  8.  —  The  nervous  system  as  a  whole.  On  the  left  it  is  seen  from  the  side  in 
position  in  the  body;  on  the  right  exposed  and  seen  from  the  front.  Ccr.,  the  cere- 
brum; Cb.,  the  cerebellum;  Sp.C,  the  spinal  cord;  P,  the  pons;  M,  the  medulla. 
The  other  letters  designate  nerve  trunks  going  to  the  central  nervous  system  and 
connections  with  the  sympathetic  system.    (After  Bougery.) 


DEVELOPMENT  OF   EMBRYO  27 

gray  matter  is  a  mass  of  cells,  the  white  a  mass  of  axones. 
Separate  masses  of  cells  are  known  as  ganglia. 

The  structures  of  the  nervous  system  may  also  be 
grouped  with  reference  to  function.  From  this  stand- 
point cells  and  fibres  may  be  divided  into  sensory  or  affer- 
ent, associative  or  commissural,  and  motor  or  efferent. 
The  sensory  neurones  are  connected  with  sense  organs,  di- 
rectly or  indirectly.  The  axones  conduct  from  the  periph- 
ery to  the  centre.  The  first  cells  of  sensory  ganglia  are 
outside  of  the  central  nervous  system,  either  in  the  sense 
organ,  or  in  ganglia  near  the  central  nervous  system,  and 
their  axones  connect  with  other  cells  nearer  the  brain.  The 
commissural  cells  and  fibres  transfer  the  impression  from 
sensory  cells  to  motor  cells.  The  motor  or  efferent  neu- 
rones stand  in  immediate  connection  with  the  muscles,  or 
with  neurones  which  serve  to  innervate  the  muscles,  —  are 
members  of  the  chain  that  conducts  impulses  from  the  cen- 
tres outward.  The  neurones  that  possess  these  different 
functions  cannot  be  distinguished  structurally.  The  func- 
tions depend  rather  upon  the  connections  in  which  the 
neurones  are  found  than  upon  their  structures. 

Development  of  Embryo.  —  To  understand  the  struc- 
tural relations,  one  must  go  back  to  the  development  of 
the  nervous  system  as  a  whole.  Many  relations,  very 
complicated  in  the  developed  organism,  are  very  simple  in 
the  earlier  stages.  The  complexities  are  caused  by  the  con- 
ditions of  growth.  Our  sketch  of  the  development  must 
be  very  brief,  with  many  omissions,  but  even  this  may  be 
helpful  at  some  points.  The  complete  adult  is  developed 
from  an  original  cell,  the  fertilized  ovum,  by  a  process  of 
division.  The  original  cell  divides  into  two,  each  of  these 
into  two,  and  so  on.  At  first  the  derived  cells  are  exactly 
like  the  original  so  far  as  can  be  made  out.     They  are 


28 


FUNDAMENTALS   OF   PSYCHOLOGY 


grouped  compactly.  The  first  sign  of  differentiation  comes 
when  a  hollow  appears  within  the  mass,  and  the  enclosing 
cells  divide  into  two  layers,  an  outer,  the  ectoderm,  and  an 
inner,  the  entoderm.  Soon  a  third  intermediate  layer 
develops  from   the   others   to   constitute    the    mesoderm. 


Fig.  q. — Embryo  of  a  rabbit  at  eight  days  to  show  the  neural  groove,    rj  is  the 
neural  groove;    h,  the  region  in  which  the  fore-brain  is  to  develop.    (From  KoUiker.) 

These  layers  may  be  distinguished  throughout  the  remaining 
development  and  give  rise  to  different  parts  of  the  organism. 
The  entoderm  gives  rise  to  the  inner  wall  of  the  internal 
organs,  and  to  certain  organs,  as  the  liver  and  pancreas. 
From  the  mesoderm  develop  the  supporting  structures, 
connective  tissue,  bone,  muscle,  and  the  body  of  most  of 


DEVELOPMENT  OF  THE  NERVOUS  SYSTEM     29 

the  internal  organs.  The  ectoderm  develops  into  the  skin 
and  its  appendages,  the  mucous  membrane  of  the  mouth 
and  nose,  and,  what  concerns  us  most,  into  the  nervous 
system  and  the  nervous  parts  of  the  sense  organs. 

The  Development  of  the  Nervous  System.  —  It  is  inter- 
esting to  note  how  the  outer  layer  of  the  embryo  gives  rise 

G 


Fig.  10.  —  Closing  of  the  neural  groove.  The  figure  at  the  top  shows  the  groove 
still  open;  in  the  next,  the  sides  approximate  each  other;  in  the  lowest,  the  closure 
is  complete.  G,  the  cells  from  which  the  spinal  ganglia  develop,-  a,  the  ectoderm; 
b,  the  epithelial  lining  of  the  medullary  tube. 

to  the  nervous  system  which  finally  becomes  embedded  so 
deeply  in  the  structure  of  the  body.  Very  early  in  the 
embryonic  Kfe,  within  the  first  two  weeks,  there  appears 
upon  the  surface  of  the  embryo  a  slight  depression  known 
as  the  neural  groove  (Fig.  9).  This  gradually  grows  deeper, 
and  finally  the  upper  edges  grow  together  and  form  the 


30 


FUNDAMENTALS   OF   PSYCHOLOGY 


neural  tube  (Fig.  lo).  From  the  walls  of  this  tube  the  entire 
nervous  system  grows.  The  forward  end  becomes  the 
brain,  the  other  longer  portion,  the  spinal  cord.  The  cells 
that  line  the  tube  give  off  first  masses  of  cells  with  radiating 
fibres  that  serve  as    a  supporting    structure   or   scaffold 


Fig.  II.  —  The  ependymal  or  supporting  structure  of  the  embryo  cord. 
(From  Cajal.) 

(Fig.  1 1).  Some  at  least  of  these  develop  later  into  neuroglia 
cells,  the  supporting  tissue  of  the  central  nervous  system. 
This  first  supporting  structure  takes  the  general  form  of 
and  may  be  said  to  prepare  the  way  for  the  truly  nervous 
structure.  After  the  supporting  or  ependymal  structure  is 
well  developed,  later  divisions  of  the  cells  lining  the  tube 
give  rise  to  embryo  neurones  or  neuroblasts.    These  make 


DEVELOPMENT  OF  THE  NERVOUS  SYSTEM     31 


Fig.  12.  —  Epithelial  cells  lining  the  neural 
tube  and  germinal  cells,  .4 ,  that  have  developed 
from  them.     (From  Cajai,  alter  His.) 


their  way  outward  toward  the  position  they  are  to  occupy 
in  the  adult  cord.  As 
the  neuroblasts  develop 
they  send  out  processes, 
axones  and  dendrites. 
The  axones  grow  out- 
ward to  the  structures 
they  are  to  supply.  A 
section  of  the  cord  at  the 
end  of  the  first  month 
shows  a  layer  of  epithe- 
lial cells  about  the  cen- 
tral tube,  farther  out  the 
neuroblasts  and  then  the 
axones  (Fig.  13).  Every- 
where in  the  brain  as  well  as  here  in  the  cord  the  principle 
holds  that  the  processes  are  outgrowths  of  the  cell  bodies. 

The  axones  grow  out 
from  the  cells  up  the  cord 
to  the  higher  centres,  and 
on  the  ventral  side  in 
particular  outward  to  the 
muscles,  even  to  the  re- 
mote parts  of  the  body. 
Meanwhile  the  sensory 
neurones  are  developing 
in  the  dorsal  ganglia. 
When  the  walls  of  the 
neural  groove  grow  to- 
gether to  form  the  tube. 

Fig.    13.  —  Schematic    section  of  embryo  ,.  r    ,,  ,      , 
cord.    /I,  anterior  or  motor  root;  £,  posterior  POrtlOnS  ot   the  ectoderm 
root;    C,    central    canal;    a,    epithelial    wall;  g^j-g     (-y^     Qff     both     from 
h,  neuroblasts  or  embryo  neurons;   c,  the  pri- 
mordial white  matter.     (Cajal,  after  His.)  the    tubc    and    frOm    the 


32 


FUNDAMENTALS   OF   PSYCHOLOGY 


surface.  They  move  away  from  the  median  plane,  and  are 
surrounded  by  mesoderm  tissue.  The  original  ectoderm 
cells  give  rise  to  neurones.     At  first  the  processes  of  the 


Fig.  14.  —  Development  of  dorsal  root  ganglion  with  cord.  A,  motor  nerve; 
5, -posterior  root,  fibres  from  ganglion  entering  cord;  E,  'T '-shaped  cells  of  dorsal 
ganglion  in  their  bipolar  stage;  e,  sensory  nerve,  dendrites  of  'T '-shaped  cells. 
(From  Cajal.) 

neurones  grow  out  from  either  end;  one  goes  outward  to 
the  end  organ  in  skin  and  muscle,  the  other  grows  into  the 
cord  and  sends  fibres  upward  in  the  back  part  of  the  cord 
or  into  the  central  gray.  Later  in  the  development,  the  two 
processes  grow  together  for  a  short  distance  from  the  cell 


ANTERIOR  PORTION  OF  THE  NEURAL  TUBE    33 

and  then  grow  off  at  right  angles  to  the  original  stem.  They 
thus  resemble  a  'T,'  and  the  cells  are  known  as  the  'T'- 
shaped  cells.  Before  birth  the  germinal  layer  stops  giving 
rise  to  new  cells  and  forms  a  single  layer  of  cells  hning  the 
central  tube. 

The  Development  of  the  Anterior  Portion  of  the  Neural 
Tube.  —  The  growth  of  the  forward  end  of  the  neural  tube, 


Thalamus 

Corpora  Quadrigemina 

Cerebrum 

f^ 

\X         Midbrain 

^ 

mj,2 

¥. 

JSm^—Bmdhrmn 
^1^- Cerebellum 

Forebrain 

Pons 
Tweenbrain 

m 

i^^^MeduUa 
\^R«-Afterbrain 

Fig.  15.  — The  five-vesicle  stage  of  the  human'brain,  giving  names  of  vesicles: 
fore-brain,  tween-brain,  etc.,  and  the  parts  of  the  adult  brain  that  develop  from 
each.    (After  His.) 

the  part  from  which  the  brain  develops,  follows  much  the 
same  plan.  The  supporting  structure  and  the  neuroblasts 
appear  as  in  the  cord.  One  difference  should  be  emphasized, 
however,  that  the  neuroblasts  are  projected  farther  from 
the  tube  and  the  axones  grow  inward  and  extend  up  or  down 
within  the  masses  of  cells.  In  consequence  the  white  matter 
is,  for  the  most  part,  within;  the  gray,  on  the  surface.  One 
other  problem  upon  which  development  throws  considerable 


34  FUNDAMENTALS  OF  PSYCHOLOGY 

light  is  in  the  longitudmal  arrangement  of  the  parts.  By 
the  end  of  the  second  week,  the  forward  end  of  the  tube 
bends  sharply  downward,  ventrally,  and  becomes  divided 
into  separate  pouches  or  vesicles.  At  first  three,  later  five, 
vesicles  are  to  be  seen.  These  are  marked  by  constrictions 
in  the  tube  at  four  places.    Two  most  marked  are  just  before 

and  just  behind  the  bend 
in  the  tube.  The  vesicle 
between  is  the  mid-brain. 
The  region  in  front  is 
divided  by  a  shallower 
groove  into  end-brain  or 
fore-brain,  and  tween- 
brain,    while    the    portion 

Fig.  1 6.  — Development  of  brain  vesicles      j^g^     behind      is     similarly 
seen  from  above.     The  hemispheres  may      ^  _  v-     j 

be  seen  growing  from  sides  of  fore-brain.      divided      intO       the      hind- 

^^'^^^■^  brain  and  after-brain. 

These  early  divisions  give  the  name  to  the  corresponding 
parts  of  the  adult  nervous  system.  The  cerebrum  develops 
from  the  fore-brain,  the  thalamus,  and  other  parts  from 
the  tween-brain,  the  corpora  quadrigemina  and  other  struc- 
tures from  the  mid-brain,  the  cerebellum  and  pons  from 
the  hind-brain,  and  the  medulla  from  the  after-brain.  Li 
each  the  walls  are  very  much  thickened  and  at  many 
points  there  are  very  large  outgrowths,  but  all  grow  from 
the  Hning  of  the  original  tube  by  the  process  of  cell  divi- 
sion indicated  above.  The  original  cavity  undergoes 
changes  of  shape  in  many  places.  It  becomes  much 
heightened  in  the  hind-brain  to  constitute  the  fourth  ven- 
tricle, in  the  mid-brain  it  retains  its  original  shape,  and 
continues  small  as  the  aqueduct  of  Sylvius.  It  broadens 
in  the  tween-brain  to  the  third  ventricle  and  bifurcates  in 
the  cerebral  hemispheres  to  form  the  lateral  or  first  and 


THE   CEREBRUM  35 

second  ventricles.  Nevertheless  it  remains  continuous 
throughout  from  the  lateral  ventricles  in  front  to  the 
bottom  of  the  spinal  cord.  It  is  filled  everywhere  with  the 
cerebro-spinal  fluid. 

The  Cerebrum.  —  The  development  of  the  cerebral 
hemispheres  deserves  special  mention.  They  appear  early 
as  lateral  swellings  on  the  fore-brain.  These  grow  first  to 
the  side,  then  upward  and  back  until  they  cover  mid-brain 


Fig.  17.  —  Shows  development  of  the  hemisphere,  the  left  figure  at  three  months, 
the  right  at  six  months,  fs  is  the  fissure  of  Sylvius;  c,  the  cerebellum;  m,  the 
mid-brain.    (From  KoUiker.) 

and  cerebellum,  an  outgrowth  of  the  original  hind-brain. 
The  two  hemispheres  are  distinct  from  the  beginning.  They 
merely  come  into  contact  along  the  median  fissure;  there 
is  no  organic  connection  between  them  except  at  the  base. 
In  this  growth  backward,  the  cerebral  hemispheres  are 
folded  here  and  there,  and  these  folds  account  for  some  of 
the  permanent  markings  upon  its  surface.  Most  striking 
of  these  is  the  fissure  of  Sylvius.  This  can  be  seen  from  the 
second  month.  It  develops  in  very  much  the  same  way  as 
the  median  fissure  from  the  growing  together  of  two  out- 
growths of  the  cerebral  hemispheres.    When  these  come  into 


36  FUNDAMENTALS   OF  PSYCHOLOGY 

contact  on  the  surface,  they  leave  considerable  portions  ot 
their  superficial  areas  in  juxtaposition  well  below  the  surface. 
The  walls  of  this  deep  fissure  constitute  the  island  of  Reil. 

In  the  course  of  the  development,  then,  we  find  neurones 
originating  from  the  cells  that  lined  the  central  tube. 
Masses  of  nerve  cells  in  the  cord  constitute  a  continuous 
structure.  In  the  cerebrum  and  cerebellum  they  show  an 
exuberant  growth  in  comparatively  isolated  regions,  sepa- 
rated from  other  cell  masses  by  regions  of  white  matter. 
From  these  cells  the  axones  grow  out  for  long  distances  to 
the  sense  organs  and  to  the  muscles  on  the  peripheral  side 
and  to  the  other  cell  masses  in  central  structures,  until 
sense  organ  is  connected  with  muscle,  and  centre  with  centre 
throughout  the  organism.  The  problem  of  understanding 
the  nervous  system  is  very  largely  one  of  tracing  these  con- 
necting paths  from  sense  organ  to  centre,  and  from  centre 
to  centre  within  the  entire  system. 

Important  Facts  of  Nervous  Conduction.  —  The  function 
of  a  nerve  unit  is  to  conduct  something  which  we  call  the 
nerve  impulse  from  the  end  of  the  dendrite  to  the  end-brush 
or  muscle.  The  question  at  once  arises,  what  is  it  that  is 
conducted,  what  is  the  nature  of  the  nerve  impulse?  Two 
answers  have  been  suggested:  one,  that  it  is  an  electric 
current;  the  other,  that  it  is  similar  to  the  burning  of  a  train 
of  gunpowder.  Five  experimentally  determined  facts  must 
be  considered  before  we  can  draw  conclusions. 

1.  The  rate  of  the  impulse  in  man  is  from  loo  to 
123  metres  per  second,  according  to  Piper.  This  is  so 
slow  as  to  make  it  impossible  to  regard  the  nerve  im- 
pulse as  merely  an  electric  current. 

2.  The  impulse  is  accompanied  by  relatively  sUght 
fatigue.  Nerves  have  been  stimulated  for  several  hours 
and  will  still  conduct. 


THE  NATURE  OF  THE  NERVE  IMPULSE  37 

3.  It  uses  very  little  oxygen,  although  oxygen  is 
required  if  the  nerve  is  to  conduct. 

4.  Carbon  dioxide  is  given  off,  but  at  a  relatively 
slow  rate. 

5.  Only  extremely  small  amounts  of  heat  are  pro- 
duced by  the  action  of  the  nerve. 

These  facts  together  indicate  that  the  energy  changes  in 
conduction  are  relatively  sHght  and  would  eliminate  the 
possibility  that  it  is  like  the  burning  of  a  train  of  gun- 
powder. Important  in  any  theory  are  the  electrical  changes 
which  have  been  seen  to  accompany  nervous  action.  Two 
currents  are  to  be  noticed:  the  current  of  rest  and  the 
current  of  action.  Both  may  be  measured  by  a  galva- 
nometer which  connects  the  cut  end  of  a  nerve  with  its  side. 
When  the  nerve  is  not  stimulated  a  current  passes  from  the 
side  to  the  cut  end;  when  the  nerve  is  excited  the  current 
passes  in  the  opposite  direction.  The  cut  end  is  negative 
when  at  rest  and  positive  when  excited.  More  important 
are  recent  results  which  show  that  as  an  impulse  passes 
along  a  nerve,  the  excited  portion  is  always  negatively 
charged  as  compared  with  the  unexcited  portion.  This 
negative  charge  moves  at  the  rate  of  the  nerve  impulse. 
These  results  show  that  while  the  nerve  impulse  is  not 
identical  with  the  electric  current,  electric  currents  are 
involved  in  the  transmission  of  the  nerve  impulse. 

The  Nature  of  the  Nerve  Impulse.  —  While  the  facts 
enumerated  in  the  last  paragraph  eliminate  the  two  most 
simple  possibilities:  that  the  nerve  impulse  is  an  electric 
current  and  that  it  is  a  transmission  of  a  chemical  change 
hke  that  of  the  burning  fuse,  they  show  that  both  chemical 
and  electrical  phenomena  are  involved.  The  simplest  pic- 
ture is  that  the  nerve  impulse  involves  both  chemical  and 
electrical  processes,  that  it  is  excited  by  a  chemical  change 


38  FUNDAMENTALS   OF  PSYCHOLOGY 

which  starts  short  electrical  currents  as  does  the  chemical 
action  in  a  battery.  These  electric  currents  in  turn  produce 
new  chemical  changes  at  a  short  distance  which  again  give 
rise  to  currents.  Many  more  details  need  to  be  suppHed, 
but  there  is  fairly  general  agreement  that  both  chemical 
and  electrical  activities  are  involved  in  the  nervous  impulse. 
Like  all  chemical  reactions  these  have  electrical  effects  and 
accompaniments.  The  chemical  changes  are  comparatively 
slight  but  suffice  to  induce  the  electric  currents.  Whatever 
the  character  of  this  nervous  impulse,  it  constitutes  the 
essential  activity  of  the  neurone,  and  as  it  travels  from 
sense  organ  to  centre  or  from  centre  to  muscle,  the  processes 
of  sensation  or  of  movement  are  made  possible. 

The  Course  of  the  Impulse.  —  The  specific  activities  of 
the  nervous  system  depend  upon  the  course  that  the  impulse 
takes  through  it.  The  simplest  form  of  nervous  response 
that  an  organism  makes  is  called  the  reflex.  It  is  the  type 
of  all  nervous  action.  The  winking  of  the  eye,  the  with- 
drawal of  the  hand  when  burned,  are  primarily  reflexes. 
The  explanation  of  the  reflex  is  to  be  found  in  the  presence 
of  chains  of  neurones  between  the  sense  organ  excited  and 
the  muscle  producing  the  response.  The  simplest  reflex 
involves  at  least  two  groups  of  neurones,  a  sensory  and  a 
motor.  It  can  be  seen  most  clearly  in  the  spinal  cord.  If 
a  finger  be  pricked,  an  impulse  passes  to  the  cell  body  of  a 
neurone  in  the  spinal  ganghon,  thence  along  the  axone  to 
the  motor  cell  in  the  front  of  the  cord,  whose  activity  causes 
the  muscles  of  the  arm  to  contract  and  draw  back  the  hand. 
That  these  reflexes  depend  upon  the  nervous  connections 
in  the  cord  and  upon  these  alone  is  evident  from  the  fact 
that  they  persist  in  the  lower  animals  after  the  cord  has 
been  cut  off  from  the  brain,  but  cease  if  the  cord  is  destroyed 
or  the  nerves  that  lead  to  or  away  from  it  be  severed.    In  a 


REFLEXES  IN  THE   CORD  39 

frog,  whose  head  has  been  removed  or  whose  cord  has  been 
cut  in  its  upper  part,  the  reflexes  persist.  Stimulation  of  the 
skin  causes  movements  of  the  members.  Even  a  dog  may 
be  kept  alive  after  its  brain  has  been  removed,  and  this 
'spinal  dog,'  as  it  is  called,  carries  on  the  reflex  activities  of 
the  lower  body  in  a  perfectly  normal  way.  When  stimulated 
on  the  skin  of  one  foot,  that  foot  will  be  drawn  back.  If 
the  intensity  of  the  stimulation  be  increased,  the  opposite 
member  is  moved,  and  as  the  stimulation  is  still  further  in- 
creased in  intensity,  movements  up  and  down  the  trunk 
at  many  different  levels  will  be  made.  In  the  frog,  for 
example,  if  a  bit  of  paper  be  dipped  in  acid  and  put  upon 
the  skin  of  the  right  thigh,  the  first  effect  is  to  bring  the 
right  foot  up  in  an  attempt  to  wipe  away  the  paper;  if  that 
foot  be  held,  the  other  will  be  brought  across  and  remove 
the  stimulation. 

The  Spinal  Cord 

Reflexes  in  the  Cord.  —  To  understand  these  reflexes 
as  well  as  most  of  the  activities  of  the  lower  part  of  the  body 
it  is  necessary  to  sketch  the  structure  of  the  spinal  cord. 
The  cord  contains  an  inner  mass  of  gray  matter,  somewhat 
like  an  H  in  shape  when  seen  in  cross  section,  surrounded  by 
columns  of  white  matter.  The  extensions  of  the  gray  matter 
are  known  as  the  horns;  the  backward  extension,  the  dorsal 
horn,  and  the  other,  the  ventral.  The  white  matter  between 
and  around  the  horns  comprises  the  columns.  The  dorsal 
horns  receive  axones  from  the  spinal  gangha.  The  anterior 
horns  contain  large  motor  cells  whose  axones  send  impulses 
to  all  of  the  muscles.  All  acts,  voluntary  as  well  as  reflex, 
are  directly  caused  by  the  excitation  of  these  cells.  The 
white  matter  is  divided  by  these  horns  into  three  columns, 
the  dorsal,  the  lateral,  and  the  ventral.    In  the  simple 


40 


FUNDAMENTALS   OF  PSYCHOLOGY 


reflex  the  sensory  impulse  is  received  by  the  neurones  in 
the  dorsal  root  ganglion,  thence  is  transmitted  by  their 
axones  across  the  gray  to  excite  the  ventral  horn  cells,  as  may 

be  seen  in  Figure  i8. 
The  sensory  neurones 
also  send  collaterals  to 
the  ventral  horn  of  the 
opposite  side.  These 
collaterals  may  con- 
nect directly  with 
motor  cells  or  they 
may  come  into  contact 
with  the  dendrites  of 
intermediate  or  com- 
missural neurones, 
whose  axones  make 
the  connections  with 
the  anterior  horn  cells. 

Fig.    1 8. —  Simple    reflex    connection    in    the  . 

cord.     C\  'T '-shaped  cell  in  the  posterior  root  Ihe  pomtS  Ot    COUtaCt 

ganglion;  .iV  sensory  neurone;  A,  dendrite  or  ^f  aXOUCS  and  deU- 
teledendnon  of  sense  organ  in  skin;   C^,  motor 

cell,    connecting    by    axone  n    with   muscle   M.  driteS     are  knOWn     aS 

(From  Huber.)  ^i                     .  rr-ii 

the  synapses.  These 
oflfer  resistance  to  the  passage  of  the  impulse,  and  synapses 
differ  in  the  amount  of  resistance  they  offer.  This  differ- 
ence in  resistance  determines  the  course  of  the  reflex. 
Thus  the  synapses  to  the  motor  neurones  which  excite  the 
muscle  of  the  side  of  the  body  stimulated  are  most  perme- 
able, and  in  consequence  the  first  and  usual  movement  is 
made  by  the  member  on  the  same  side.  It  is  only  when 
the  stimulus  becomes  stronger  that  the  member  opposite 
moves.  The  neurones  in  the  spinal  ganglia  also  send  col- 
laterals up  and  down  in  the  cord,  which  connect  directly  or 
through  commissural  neurones  with  the  motor  neurones  at 


REFLEXES  IN  THE   CORD 


Hgu  i  ill 


:^ 


41 


If  I 


^^i 


42  FUNDAMENTALS   OF  PSYCHOLOGY 

various  levels  (Fig.  19).  These  make  possible  reflex  exci- 
tation of  groups  of  muscles  above  and  below  the  point  of 
stimulation.  These  cord  reflexes  are  all  to  be  explained  in 
terms  of  the  connections  between  sensory  and  motor  neu- 
rones. What  the  response  shall  be  is  determined  by  the  de- 
gree of  openness  of  the  synapses  between  different  neurones. 
Tracts  in  the  Cord.  —  In  addition  to  the  reflex  functions 
of  the  cord,  it  also  serves  as  an  important  path  of  conduction 
between  the  periphery  and  the  higher  structures  of  the  cen- 
tral nervous  system,  and  between  its  own  structures  at  dif- 
ferent levels.  The  conduction  paths  may  be  divided  into 
sensory  or  afferent,  and  motor  or  efferent.  The  sensory 
fibres  all  come,  directly  or  indirectly,  from  the  dorsal  roots 
and  the  spinal  gangha;  the  motor  tracts  all  end  in  the  cells 
of  the  ventral  horn.  The  different  tracts  are  to  be  distin- 
guished in  terms  of  the  higher  centres  to  which  they  lead 
or  from  which  they  descend.  The  most  important  of  the 
higher  centres  with  which  the  cord  connects  are  the  cere- 
bellum, which  receives  ascending  or  sensory  tracts  and  from 
which  motor  paths  descend  directly  and  by  way  of  the  red 
nucleus;  the  corpora  quadrigemina,  from  which  smaU 
tracts  descend  and  to  which  they  ascend;  the  thalamus,  to 
which  sensory  fibres  go  on  the  way  to  the  cerebral  cortex; 
and  the  cortex  itself,  the  outer  layers  of  the  cerebrum. 
From  this  descend  two  tracts,  whose  fibres'  carry  voluntary 
impulses  to  the  muscles  of  the  body.  Of  the  afferent  tracts, 
the  most  easily  made  out  are  the  columns  of  Goll  and  Bur- 
dach  on  the  dorsal  side.  These  occupy  most  of  the  region 
between  the  dorsal  horns.  The  column  of  Goll  is  nearer 
the  centre,  the  column  of  Burdach  more  lateral.  Each  is 
composed  of  fibres  from  the  spinal  ganglia,  axones  of 
neurones  in  the  ganglia.  The  only  difference  is  that  the 
more  lateral  fibres  come  from  parts  of  the  body  on  approxi- 


TRACTS   IN  THE   CORD 


43 


mately  the  same  level,  which  have  just  entered  the  cord; 
the  more  central  have  entered  lower  down  and  have  been 
crowded  toward  the  centre  by  those  that  come  in  later. 
Both  groups  of  fibres  end  in  the  medulla  and  there  make 
connections  with  neurones  which   send  impulses   to   the 


Ascending  {Centripda')  Trade. 
I=Long    fibres   of   the    posterior 
roots. 
II  =Sprao-cerebellar  tracts  {a,  dor- 
sal ;     6,     ventral  =tract     of 
Gowers). 
lII=Spiuo-thalamio  tract. 


Descending  {Cenlrijuoal)  Tracts. 
I  l=Cortico-spinal  tracts    (a,  lateral 

I  pyramid     tract ;     6,     anterior 

I  pyramid  tract). 

2-5  =  Subcortico-spinal  tracts  (2, 
rubro-spinal  and  thalamn- 
spinal  ;  3,  vestibulo-spinal  ; 
4,  tecto-spinal). 
6.  Descending 
fibres  of  the 
dorsal  column. 


ToPOORArHY    OF   THE    LONQ    SPIHAL  TRACTS. 

Fig.  20. — Paths  of  conduction  in  cord.     (From  Bing's  "Compendium  of  Regional 
Diagnosis."     Published  by  Rebman  Bros.,  New  York.) 

thalamus  and  thence  to  the  cortex.  Their  chief  function 
is  to  transmit  impulses  from  the  muscles.  In  the  same  area 
is  the  so-called  'comma'  tract,  named  from  its  shape,  which 
consists  of  collaterals  from  entering  neurones  that  turn 
downward  to  connect  with  motor  cells  lower  in  the  cord. 

Other  well-marked  afferent  tracts  are  found  on  the  lateral 
border  of  the  cord,  the  cerebellar  tracts.  They  are  divided 
into  two,  the  more  dorsal  tract  of  Flechsig  and  the  more  ven- 


44  FUNDAMENTALS   OF  PSYCHOLOGY 

tral  tract  of  Gowers.  Both  are  derived  from  cells  in  the 
dorsal  gray  of  the  cord  and  carry  impulses  to  the  cerebellum. 
Still  another  sensory  tract  of  importance  Hes  within  Gowers' 
tract.  It  is  marked  spino-thalamic  in  Figure  20  and  con- 
stitutes part  of  the  pathway  from  the  skin  to  the  cortex. 
Sensory  impulses  from  the  skin  are  carried  by  axones  from 
the  'T'-shaped  cells  in  the  spinal  root  ganglia  into  the  gray 
of  the  cord.  There  they  connect  with  a  second  set  of  neu- 
rones whose  cell-bodies  he  near  the  spinal  canal.  The  axones 
from  these  cells  cross  and  in  part  go  up  this  spino-thalamic 
tract  to  the  thalamus  and  thence  to  the  cortex.  The  tract 
may  also  contain  some  fibres  leading  to  the  corpora  quadri- 
gemina. 

Motor  Tracts.  —  Of  the  descending  or  motor  fibres  the 
most  important  are  found  in  the  pyramidal  tracts.  There 
are  two  pyramidal  tracts,  the  crossed  and  the  uncrossed. 
The  former,  always  the  larger,  hes  just  inside  the  Flechsig 
tract  and  is  very  close  to  the  dorsal  horn  of  gray  matter. 
The  uncrossed  pyramidal  tract  lines  the  ventral  fissure  of 
the  cord.  Both  tracts  are  composed  of  axones  of  cells  in 
the  cerebrum,  which  descend  to  make  connection  with  the 
anterior  horn  cells.  They  carry  the  voluntary  impulses. 
The  fijst  mentioned  is  composed  of  fibres  that  cross  in  the 
medulla;  the  second  or  anterior,  of  fibres  that  have  con- 
tinued down  on  the  same  side  but  cross  in  the  cord  near  the 
level  of  the  cells  with  which  they  connect.  Other  bundles 
descend  from  the  cerebellum.  One,  coming  by  way  of  the 
red  nucleus,  the  rubro-spinal  (Fig.  20),  hes  ventral  to  the 
lateral  pyramids;  the  other  is  on  the  ventral  border. 
Mention  should  also  be  made  of  a  bundle  from  the  corpora 
quadrigemina,  the  tecto-spinal,  on  the  ventral  border  of 
the  anterior  horn.  It  should  be  noted  that  the  names  ap- 
phed  in  each  instance  indicate  the  structures  connected :  the 


MOTOR  TRACTS  45 

cortico-spinal  tract  connects  cortex  with  cord;  spino- thala- 
mic, cord  with  the  thalamus,  etc. 

In  addition  to  these  long  bundles  running  from  cells  at 
one  level  to  others  above  and  below,  there  are  many  fibres 
which  make  possible  the  transfer  of  impulses  within  the 


^l 


B 


A 

Fig.  21.  —  Series  of  sections  of  the  cord  to  indicate  difference  in  the  amount  of 
white  and  gray  and  the  relative  size  of  the  cord  at  the  different  levels.  B  is  a  sec- 
tion through  the  lumbar  enlargement,  where  the  nerves  of  the  legs  enter  and  leave; 
D,  a  section  through  the  cervical  enlargement  which  supplies  the  arms.  This  figure, 
together  with  figures  23,  24,  25.  and  31,  was  drawn  by  Mr.  Atwell  of  the  Anatomical 
Laboratory  of  the  University  of  Michigan. 

cord.  These  are  numerous  at  the  borders  of  the  gray  matter, 
but  also  occupy  parts  of  the  white  area  that  have  been  as- 
signed no  other  function  in  the  above  discussion.  Probably 
some  of  the  sensory  impressions  pass  along  the.se  fibres  on 
their  way  to  the  brain.  They  go  from  neurone  to  neurone, 
into  the  central  gray  and  out  again,  instead  of  taking  the 
more  direct  course  provided  by  the  long  fibres.  It  should 
be  added  that  the  arrangement  of  fibres  is  different  at 
different  levels.     The  pyramidal  tracts,  for  example,  are 


46  FUNDAMENTALS   OF  PSYCHOLOGY 

much  larger  in  the  upper  portions  of  the  cord,  as  some  of 
the  fibres  that  appear  at  the  upper  level  leave  it  to  make 
connections  with  the  ventral  horn  cells.  In  fact,  the  ventral 
tract  cannot  be  made  out  at  all  in  the  lower  regions.  The 
relative  amount  of  white  and  gray  matter  also  varies  at 
different  levels.  The  gray  matter  has  the  greatest  extent 
in  the  lower  lumbar  region  and  in  the  cervical  region,  where 
the  large  nerves  for  the  legs  and  arms  enter  and  emerge. 
The  cord  as  a  whole  also  increases  in  cross  section  from 
below  upward,  with  marked  swellings  where  the  large  nerves 
enter.     See  Figure  21. 

The  Brain  Stem 
Functions  of  the  Brain  Stem.  —  In  the  brain  stem,  from 
the  medulla  upward,  the  structure  of  the  nervous  system 
becomes  much  more  compHcated,  but  the  functions  and 
general  arrangements  are  much  the  same.  We  may  dis- 
tinguish three  functions  of  the  structures  in  the  brain  stem : 

1.  Fibres  massed  in  well-defined  tracts  carry  the 
sensory  impressions  upward  and  motor  impulses  down- 
ward between  cord  and  cerebrum. 

2.  Masses  of  neurones  care  for  the  reflexes  of  the 
head  in  very  much  the  same  way  that  the  cord  cares 
for  those  of  the  body.  Nerves  lead  into  them  from 
the  special  sense  organs  and  from  the  skin  of  the  head, 
and  motor  nerves  lead  out  from  them  to  the  muscles 
of  the  head  just  as  sensory  nerves  lead  into,  and  motor 
nerves  go  out  from,  the  cord. 

3.  The  brain  stem  also  makes  wider  interconnec- 
tions, —  serves  to  combine  large  numbers  of  sensory 
stimuli  from  different  sense  organs  and  to  combine  and 
distribute  them  in  exciting  muscles  in  widely  scattered 
parts  of  the  body  to  make  harmonious  movements. 


STRUCTURES   IN  THE   BRAIN   STEM        47 


Making  the  different  parts  of  the  body  work  together 
is  the  pecuUar  function  of  the  nervous  system.  The  coor- 
dinations in  the  brain  stem  are  wider  than  those  in  the 
cord  and  those  of  the  cerebrum  are  widest  of  all. 

Important  Structures  in  the  Brain  Stem.  —  To  trace  the 
ascending  and  descending  paths  of  impressions,  we  need  to 
distinguish  several 
structures  in  the 
brain  stem  that 
serve  as  way  sta- 
tions, points  where 
impulses  are  trans- 
ferred from  the 
axone  of  a  lower 
neurone  to  the 
dendrites  of  a  neu- 
rone that  carries 
them  upward,  or 
where  descending 
impulses  are  inter- 
rupted and  trans- 
ferred to  new  neu- 
rones. The  first 
are  in  the  medulla, 
the  so-called  nuclei 
of  Goll  and  Bur- 
dach  (Figs.  23,  24).  These,  with  the  thalamus,  are  parts 
of  the  pathway  of  sensory  impulses  from  the  trunk  and 
hmbs.  The  thalamus  is  a  structure  at  the  base  of  the 
cerebrum  which  can  be  seen  in  a  median  section  of  the 
nervous  system  on  the  walls  of  the  third  ventricle,  or  from 
above  in  Figure  22.  Below  it  to  one  side  may  be  seen  the 
internal  and  external  geniculate  bodies,  and  still  lower  lie 


Fig.  22.  —  Dorsal  view  of  brain  stem,  fg,  column 
of  Goll;  fc,  column  of  Burdach;  «,  anterior,  /,  posterior 
pair  of  corpora  quadrigemina;  /A,  thalamus;  /fe,  external 
and  k'  internal  geniculate  bodies;  x,  epiphysis  (pineal 
gland);  ps,  pm,  pi,  are  superior,  middle,  and  inferior 
peduncles  of  the  cerebellum,  which  may  itself  be  seen, 
in  part  cut  away  and  drawn  to  one  side.  (From 
Wundt.) 


48  FUNDAMENTALS   OF  PSYCHOLOGY 

the  corpora  quadrigemina.  These  are  both  receiving  organs 
for  certain  of  the  fibres  from  eye  and  ear,  and  will  be  men- 
tioned in  connection  with  these  sense  organs.  The  red 
nucleus  lies  within  the  body  of  the  brain  stem  below  the 
back  portion  of  the  thalamus  and  the  corpora  quadrigemina 
(Fig.  31).  This  is  a  way  station  from  the  cerebellum  and 
also  from  the  cortex  to  the  cord.  A  part  of  the  cerebellum 
can  be  seen  drawn  to  one  side  in  Figure  22  and  the  pons  is 

Column  of  Goll 
Column  of, 
Burdach 


Fig.  23.  —  Section  of  the  medulla  to  show  the  crossing  of  the  pyramidal  tracts,  a 
section  a  httle  below  that  shown  in  Figure  24.    X  4. 

directly  in  front  of  it.    For  our  purposes  these  are  the  most 
important  structures  in  the  brain  stem. 

The  Paths  in  the  Brain  Stem 

The  Paths  between  Cord  and  Cortex.  —  Nerve  currents 
from  the  sense  organs  of  the  limbs  and  trunk  may  reach 
the  cortex  by  two  distinct  paths.  The  first,  which  probably 
carries  only  the  impulses  from  the  muscles  and  other  deeper 
lying  tissues,  is  provided  by  the  columns  of  Goll  and  Bur- 
dach. Axones  of  cell  bodies  in  the  spinal  gangha  ascend 
by  these  tracts  to  the  nuclei  of  Goll  and  Burdach.  Here 
they  come  into  contact  with  dendrites  of  other  neurones 


THE  PATHS  BETWEEN  CORD  AND  CORTEX  49 


whose  axones  cross  to  the  other  side  and  then  proceed  up 
the  central  portion  of  the  brain  stem  to  the  thalamus. 
Thence  a  third  set  of  neurones  carries  the  impulse  to  the 
cortex.  Impulses  from  the  external  skin  apparently  travel 
by  other  spinal  neurones  whose  axones  enter  the  central 
gray  of  the  cord  and  make  connections  with  dendrites  of  a 
second  neurone  whose  cell  body  lies  near  the  central  canal. 


Column  of  Goll 
Column  of, 
Burdach 


Nucleus  of  Goll 


Pyramids 


Fig.  24.  —  Section  through  the  medulla  to  show  the  crossing  of  the  sensory  fibres, 
the  axones  of  cells  in  the  nuclei  of  Goll  and  Burdach.    X  4. 

These  neurones  send  their  axones  up  the  lateral  column  of 
the  opposite  side  to  the  thalamus.  The  exact  path  that  is 
followed  in  the  lateral  column  is  not  definitely  agreed  upon. 
Some  authors  believe  that  there  is  a  long  tract  in  the  an- 
terior portion  of  the  lateral  column,  the  spino-thalamic 
tract  in  Figure  20;  others  that  the  path  goes  by  way  of 
short  fibres  near  the  gray  and  perhaps  may  be  interrupted 
at  different  levels.  The  axone  may  reenter  the  central 
gray  several  times,  connect  with  a  new  neurone,  and  have 
that  neurone  continue  the  impulse  upward.    That  there  is 


so 


FUNDAMENTALS  OF  PSYCHOLOGY 


a  pathway  upward  on  the  side  of  the  cord  opposite  to  that 
of  the  sensory  nerve  stimulated,  and  that  this  carries  the 
cutaneous  impulses,  is  made  very  probable  by  observation 
of  pathological  cases.  Figure  26  shows  the  posterior  paths. 
The  descending  tracts  from  the  cerebrum  are  the  pyramidal 
tracts.  The  fibres  that  compose  them  are  axones  of  cells 
in  the  motor  cortex.    They  can  be  traced  on  the  anterior 


Transverse  pon 
tine  fibres 


Fig.  25.  —  Section  through  pons.  The  interlacing  of  the  descending  pyramidal 
tracts,  with  the  cross  fibres  of  the  pons,  mainly  connecting  the  lobes  of  the  cere- 
bellum, is  clearly  shown.  Above,  dorsal  to  the  pons,  may  be  seen  the  section  of 
the  fillet,  the  sensory  fibres  ascending  from  the  nuclei  in  the  medulla  to  the  thala- 
mus.   A  section  of  part  of  the  fifth  nerve  may  also  be  seen. 

portion  of  the  brain  stem  through  their  whole  course  except 
where  they  intermingle  with  the  fibres  of  the  pons,  as  can 
be  seen  in  Figure  25  (a  section  through  the  pons).  In  the 
medulla,  part  of  the  fibres  cross,  as  can  be  seen  in  the 
cross  section,  Figure  23.  These  constitute  the  crossed  pyra- 
midal tracts  already  noticed  in  the  cord.  The  uncrossed 
pyramidal  tract,  which  is  usually  smaller,  and  may  not  be 
present  at  all,  continues  down  the  anterior  column  and 
crosses  in  the  cord  at  the  level  of  the  anterior  horn  cells 


NERVES  AND  THEIR  CONNECTIONS 


51 


with  which  it  is  to  make  connection.  The  right  hemisphere 
of  the  cortex  therefore  always  arouses  movements  in  the 
left  half  of  the  body, 
and  vice  versa.  The 
course  of  these  de- 
scending fibres  also  can 
be  seen  in  Figure  26. 
Only  two  neurones  are 
required  to  transmit 
the  motor  impulse 
from  the  cortex  to  the 
muscle,  while  three  at 
least  are  concerned  in 
carrying  the  sensory 
impulse  upward. 

Roots   of   Cranial 
Nerves  and  their  Cen- 
tral   Connections. — 
The  brain  stem  is  like 
the    cord,   also,   in  its 
second  set  of 
functions,   re- 
ceiving   sensory 
fibres    and    im- 
pressions,   and 
sending  out 
motor  nerves 
and    impulses. 
UnHke  the  con- 
tinuous series  of 
cells  in  the  cord, 
the   cell    bodies 
whose  dendrites 


Fig.  26. —  Showing  ^(.lu.n.itH  .ll>  the  ascendmg  and 
descending  tracts  between  cord  and  cortex.  .4,  pyramidal 
tracts;  B,  motor  cell;  C,  D,  sensory  cells;  E,  F,  nuclei  of 
Burdach  and  of  Goll;  G,  central  sensory  path;  H,  thal- 
amus. Only  the  sensory  path  by  the  posterior  columns 
is  indicated.  The  arrows  indicate  the  direction  of  the 
impulse.     (From  Cajal.) 


52 


FUNDAMENTALS   OF  PSYCHOLOGY 


and  axones  constitute  the  so-called  cranial  nerves  are 
grouped  in  isolated  masses  of  cells  along  the  brain  stem, 
the  nuclei  of  the  cranial  nerves.  From  these  nuclei,  con- 
nections are  made  with  each  other,  with  the  cerebellum, 


Fig.  27.  —  The  central  connections  of  the  cochlear  branch  of  the  eighth  nerve, 
the  nerve  of  hearing.  The  first  layer  of  neurones  have  their  cell  bodies  in  the 
spiral  ganglia  (VIII  c)  which  correspond  to  the  spinal  root  ganglia  of  the  cord. 
Their  axones  connect  with  a  second  layer  of  neurones  either  in  the  ventral  root  of 
the  eighth  nerve  (na)  or  in  the  tuberculum  acusticum.  The  axones  from  this  sec- 
ond layer  of  cells  in  both  nuclei  go  to  the  superior  olives  (os),  some  to  the  one  on 
the  same  side  and  some  to  the  one  on  the  opposite  side.  From  the  oUves  third 
neurones  connect  with  a  fourth  layer  of  neurones  with  cells  in  the  nucleus  lemnis- 
cus lateralis  (nil)  which  carry  the  impulses  to  the  internal  geniculate  bodies  (cgm) 
and  thence  by  a  fifcn  layer  to  the  temporal  lobe  of  the  cerebrum.  Certain  of  the 
neurones  in  the  olives  send  axones  to  the  inferior  corpora  quadrigemina  {colliculus 
inf.)  where  reflex  connections  are  made  with  motor  roots  of  the  brain  stem.  (From 
Rauber-Kopsch.) 

corpora  quadrigemina,  and  cortex.  The  location  and  con- 
nection of  the  parts  would  require  more  space  and  the 
knowledge  of  more  details  of  anatomy  than  can  be  given 
in  so  brief  a  treatment.  It  may  be  said  in  general  that 
there  is  some  approximation  to  the  arrangement  of  the 


THE  OPTIC  AND  CUTANEOUS  TRACTS   53 

spinal  cord  in  that  the  motor  nerves  frequently  are  anterior 
to  the  ventricles,  while  the  sensory  roots  are  more  lateral 
or  posterior.  These  sensory  and  motor  nuclei  also  have 
connections  with  the  cortex  similar  to  those  of  the  cord. 

Connections  of  the  Auditory  Nerve.  —  We  may  trace 
the  course  to  the  cortex  of  some  of  the  more  important 
sensory  nerves  of  the  head.  The  eighth  nerve,  or  nerve  of 
hearing,  consists  of  the  axones  from  the  cells  in  the  spiral 
gangHa  in  the  ear  (Fig.  27).  These  connect  with  the 
dendrites  of  cells  in  the  root  of  the  eighth  nerve  at  the 
level  of  the  pons;  from  these,  new  neurones  carry  the  im- 
pulse to  the  superior  ohves  on  both  sides,  and  thence  by 
two  other  neurones  it  goes  forward  to  the  internal  or  me- 
dian geniculate  body,  a  body  near  the  thalamus,  and  to 
the  posterior  corpora  quadrigemina.  From  the  geniculate 
body,  one  set  of  neurones  carries  the  impression  forward 
to  the  cortex  where  hearing  takes  place.  In  the  posterior 
corpora  quadrigemina  reflex  connections  are  made  with  ear 
and  head  muscles. 

The  Optic  and  Cutaneous  Tracts.  —  The  optic  tract  is 
very  similar  (Fig.  28).  The  axones  from  the  eye  enter 
the  external  geniculate  body  and  possibly  the  visual  area  of 
the  thalamus,  thence  go  to  the  cortex.  The  fibres  that 
control  the  eye  reflexes  and  the  higher  coordinations  run 
directly  to  the  anterior  corpora  quadrigemina,  where  they 
make  connections  with  nuclei  of  the  motor  nerves  to  the 
eye.  The  fifth  nerve,  in  part  a  sensory  nerve  for  impres- 
sions from  the  skin  and  other  tissues  of  the  head,  has  its 
cells  in  a  large  ganglion,  which  has  much  the  same  relation 
to  the  brain  stem  that  the  dorsal  root  ganglia  have  to  the 
cord.  Thence  axones  connect  with  second  neurones  in  the 
nucleus  whose  axones  go  to  the  thalamus,  whence  the  third 
neurone  makes  connection  with  the  cortex   (Fig.  29).    In 


54 


FUNDAMENTALS   OF  PSYCHOLOGY 


general  the  fibres  of  all  these  nerves  cross  either  in  the 
brain  stem  or,  in  the  case  of  the  eye,  whose  fibres  cross  in 
part  only,  in  the  optic  nerve  itself.     The  fibres  from   the 


Fig.  28.  —  The  central  connections  of  the  optic  nerve.  From  the  neurones  in  the 
eye  the  axones  that  form  the  optic  nerve  extend,  after  partial  crossing  in  the  chi- 
asma,  to  the  external  geniculate  body  where  connection  is  made  with  a  second 
series  of  neurones  which  carry  the  impulse  to  the  median  surface  of  the  occipital 
lobe.  Other  axones  connect  with  the  pulvinar  of  the  thalamus  and  with  the  anterior 
corpora  quadrigemina  {Collkidus  sup.).  From  the  latter  impulses  are  carried  to 
the  roots  of  the  oculo-motor  nerves  by  the  path  fa,  through  which  reflexes  are 
aroused.    (After  Bechterew.) 


Fig.  29.  —  The  ascending  or  sensory  connections  of  the  fifth  nerve.  The  rela- 
tions are  very  similar  to  those  of  the  dorsal  roots  of  the  cord.  The  receiving  neu- 
rones have  cells  in  the  ganglion  {Ganglion  V),  send  axones  to  the  sensory  nuclei,  Vs, 
which  correspond  to  the  nuclei  of  GoU  and  Burdach  for  the  spinal  nerves,  whence 
the  new  neurones  connect  with  a  third  layer  of  neurones  whose  cell  bodies  are  in 
the  thalamus  and  which  carry  the  impulse  to  the  cortex.  (From  Rauber-Kopsch.) 
55 


56 


FUNDAMENTALS  OF  PSYCHOLOGY 


inner  halves  of  the  retinas  cross,  and  finally  reach  the  cor- 
tex on  the  opposite  side;  those  from  the  outer  halves  go  to 
the  cortex  on  the  same  side.  Corresponding  to  the  py- 
ramidal fibres  that  descend  to  the  cord,  motor  fibres  also 
descend  from  the  cortex  to  the  roots  of  the  motor  nerves 
of  the  head  and  make  possible  the  voluntary  control  of  the 
eyes,  tongue,  facial  muscles,  etc. 

Lonq  ciltari/  nerues. 
.Pilalor 


T  Ciliary  Tierves 


Fig.  30.  —  The  reflex  control  of  the  size  of  the  pupil.  The  impulse  of  dilatation 
takes  the  long  path  from  the  corpora  quadrigemina  down  to  the  cord  and  back 
through  the  cervical  sympathetic,  the  superior  cervical  ganglion,  and  out  through 
a  branch  of  the  fifth  nerve  to  the  iris.  The  impulse  to  contraction  makes  connec- 
tion through  the  third  nerve  with  the  ciliary  ganglion,  thence  to  the  iris.  (From 
Howell's  "Physiology,"  after  Schultz.) 

The  reflex  function  may  be  illustrated. by  the  contrac- 
tion of  the  pupil  in  a  bright  Hght.  As  was  said  above,  the 
optic  nerve  sends  one  branch  to  the  anterior  corpora  quad- 
rigemina. Thence  axones  proceed  to  the  roots  of  the  third 
nerve.  Neurones  there  in  turn  connect  with  the  ciliary 
ganghon  back  of  the  eye,  which  sends  the  impulse  to  the 
circular  muscle  in  the  iris.  Strong  light  causes  the  sensory 
impulse  to  ascend  to  the  corpora  quadrigemina,  whence  it 
is  transmitted  by  a  new  neurone  to  the  motor   nucleus, 


THE  FUNCTION  OF  THE  CEREBELLUM  57 

thence,  through  at  least  two  more  neurones,  to  the  muscle 
of  the  iris,  whose  contraction  diminishes  the  diameter  of 
the  pupil  (Fig.  30).  Similar  reflexes  are  seen  in  sneezing, 
which  involves  the  spinal  cord  as  well  as  the  brain  stem; 
in  making  a  wry  face  at  a  bad  taste,  etc.  In  the  medulla 
are  the  reflex  centres  that  control  respiration,  circulation, 
and  other  vital  functions.  The  details  of  the  paths,  so  far 
as  known,  may  be  obtained  from  any  good  physiology. 

Cerebellum,   Corpora  Quadrigemina,  and   Thalamus 

Connections  of  the  Cerebellum.  —  The  third  or  coor- 
dinating function  is  most  highly  developed  in  the  cerebel- 
lum and  corpora  quadrigemina.  If  we  consider  the  con- 
nections of  the  cerebellum,  it  becomes  evident  that  it  is 
closely  connected  with  the  adjustment  of  movements.  To 
it,  as  we  have  seen,  go  two  sensory  tracts  from  the  cord. 
To  it  also  go  fibres  from  the  vestibule  of  the  ear,  the  organ 
for  appreciating  the  position  of  the  body  as  a  whole.  It 
receives  fibres  from  the  cortex  and  fibres  from  the  ocular 
tracts.  From  it  go  fibres  to  the  spinal  cord  directly  and 
by  way  of  the  red  nucleus  in  the  mid-brain  just  below  the 
corpora  quadrigemina.  It  also  sends  fibres  to  the  motor 
nuclei  of  the  eye  muscles.  These  make  possible  the  move- 
ments of  the  muscles  of  the  trunk  and  head. 

The  Function  of  the  Cerebellum.  —  The  general  func- 
tion of  the  cerebellum  is  to  coordinate  muscular  move- 
ments, particularly  those  involved  in  keeping  the  balance. 
The  influence  is  best  evidenced  by  the  defects  that  appear 
when  the  cerebellum  is  injured.  Then  the  body  is  held 
erect  only  with  difficulty,  if  at  all,  the  movements  are  jerky, 
the  patient  staggers  when  walking,  the  gait  is  like  that  of 
the  drunken  man.  The  balance  of  the  body  is  not  ad- 
justed to  the  movements  of  the  legs,  the  patient  may  lean 


58  FUNDAMENTALS   OF   PSYCHOLOGY 

too  far  forward  or  too  far  back  for  the  immediate  position 
of  the  body.  Recent  work  makes  it  probable  that  certain 
parts  of  the  cortex  of  the  cerebellum  take  care  of  definite 
parts  of  the  body.  Streeter  has  established  the  locaHzation 
by  tracing  the  fibres,  Barany  by  a  study  of  the  effects  of 
injuries  of  the  cerebellar  cortex  and  by  direct  stimulation 
of  its  surface.     It  is  probable  that  the  nerve  currents  from 


Anterior  Corpora  Quadrigemina 

Internal  Geniculate  buuy 


Red  Nucleus 
Cerebral  Peduncles  Oculo-Motor  Nerves 

Fig.  31.  —  Section  of  mid-brain  to  show  position  of  red  nucleus.  The  anterior 
corpora  quadrigemina  and  the  internal  geniculate  bodies  can  also  be  seen,  as  can 
the  fibres  of  the  third  nerve,  whose  roots  receive  fibres  from  the  corpora  quadri- 
gemina on  the  way  to  the  eye  muscles.  In  the  lower  anterior  portion  the  descending 
fibres  that  constitute  the  cerebral  peduncles  may  be  seen.  The  pyramidal  tracts  are 
in  the  median  portion  of  this  structure.    X  2. 

the  various  organs,  skin,  muscle,  the  vestibules  of  the  ears 
and  the  eyes,  which  give  a  knowledge  of  position,  are  here 
united  and  coordinated  and  then  sent  out  to  the  muscles, 
where  they  produce  the  muscular  contractions  that  keep 
the  balance.  The  cerebellum  thus  serves  to  bring  together 
the  sensory  impressions  concerned  in  movement,  to  gradu- 
ate them  properly,  and  to  send  out  impulses  which  shall 
control  the  lower  reflexes,  check  some,  increase  others,  and 
make  all  work  together  in  proper  balance. 


THE   FUNCTIONS   OF  THE  THALAMUS      59 

Functions  of  Corpora  Quadrigemina.  —  From  the  fact 
that  the  corpora  quadrigemina  receive  fibres  from  skin, 
ear,  and  eye,  and  have  connections  with  the  motor  cells  in 
the  cord,  as  well  as  with  the  eye  muscles  and  other  muscles 
of  the  head,  it  seems  probable  that  this  may  be  a  similar 
coordinating  centre.  In  the  lower  animals  the  large  devel- 
opment of  these  organs,  as  compared  with  the  other  re- 
gions of  the  brain,  together  with  direct  experiment,  make 
it  seem  likely  that  many  of  the  automatic  movements  are 
coordinated  here.  In  man,  however,  this  lower  centre  of 
coordination  has  been  largely  overshadowed  in  its  func- 
tions by  the  cerebral  hemispheres,  so  that  it  plays  a  sub- 
ordinate part.  It  is  the  centre  for  reflexes  of  the  eyes,  and 
probably  for  movements  of  the  head,  but  neither  experi- 
ment nor  pathology  gives  much  evidence  of  a  coordinating 
function. 

The  Functions  of  the  Thalamus.  —  We  have  seen  that 
the  thalamus  is  a  way  station  for  impulses  from  the  skin 
and  other  sense  organs  in  their  course  to  the  cortex.  Re- 
cently evidence  has  been  accumulating  that  it  is  also 
closely  connected  with  emotional  expression.  In  emotion 
there  are  changes  in  the  circulation,  in  the  expression  of  the 
face,  and  the  secretions  in  certain  of  the  glands.  These 
responses  seem  to  be  produced  refiexly  through  the  thala- 
mus. When  the  thalamus  is  injured  the  responses  are 
changed.  Bechterew  reports  a  case  in  which  injury  to  one 
thalamus  destroyed  the  emotional  expression  of  one  side 
of  the  face  and  left  the  other  undisturbed. 

REFERENCES 
Villiger:  Brain  and  Cord. 
Herrick:  Introduction  to  Neurology. 
Howell:  Physiology,  Chs.  VI,  VII,  VIII. 
Starling:  Physiology,  Ch.  VII,  §§vii-xvi. 


CHAPTER  III 

THE  NERVOUS   SYSTEM  {Continued) 

In  the  cerebral  hemispheres  we  come  much  closer  to  the 
problems  that  primarily  concern  psychology.  Here,  we 
beheve,  the  processes  which  accompany  consciousness  in 
all  its  forms  have  their  place,  and  run  their  course.  But 
for  an  understanding  of  the  nervous  operations  themselves 
this  makes  no  difference.  The  structures  and  their  func- 
tions can  be  best  understood  on  the  analogy  of  the  lower 
parts  of  the  nervous  system.  It  is  in  its  turn  just  a  mass  of 
neurones  with  their  processes,  and  its  functions  can  be 
represented  as  due  to  the  spreading  of  impulses  along  paths 
within  it.  The  problems  that  meet  us  here  are  those  that 
have  met  us  all  the  way  up  to  this  point.  The  cerebrum 
constitutes  part  of  the  highest  and  most  complicated  path 
by  which  sensory  impressions  may  pass  over  to  the  muscles 
and  excite  muscular  contraction. 

The  Functions  of  the  Cerebrum 

The  Parts  of  the  Cerebrum.  —  In  the  cerebrum  may  be 
distinguished  three  sets  of  structures.  On  the  surface  there 
is  a  relatively  thin  layer  of  gray  matter,  a  number  of  layers 
of  neurones  with  connecting  processes,  • —  the  cortex.  This 
outer  coat  has  a  large  surface  because  of  the  great  number 
of  fissures  and  folds  that  are  found  on  its  surface.  These  are 
much  more  developed  in  man  than  in  the  animals.  Below 
the  cortical  gray  the  interior  is  largely  filled  with  white 
matter,  —  masses  of  fibres  that  run  from  the  cortex  down- 
60 


LOBES   OF   THE    CEREBRUM  6i 

ward  to  the  brain  stem,  from  one  part  of  the  hemisphere  to 
another,  or  from  one  cortex  to  the  other  through  the  corpus 
callosum  and  the  commissures.  At  the  base  of  the  cerebrum 
are  found  other  masses  of  gray  matter,  the  corpora  striata. 
These  are  divided  into  a  number  of  masses  by  the  fibres 
that  descend  from  the  cortex  to  the  brain  stem,  the  corona 
radiata.  The  function  of  the  gangha  at  the  base  of  the  cere- 
brum has  not  been  definitely  determined.  They  have  con- 
nections with  the  centres  in  the  brain  stem,  but  relatively 
few  with  the  cortex.  It  has  been  supposed  that  they  have 
something  to  do  with  the  regulation  of  the  temperature 
of  the  body.    We  need  not  consider  them  farther. 

Lobes  of  the  Cerebrum.  —  The  cerebrum  is  divided  by 
the  median  fissure  into  two  hemispheres.  Each  hemisphere 
for  convenience  of  reference  has  been  divided  into  five  lobes. 
Three  fissures  in  the  cortex  have  been  selected  as  boundaries. 
The  most  prominent  is  the  fissure  of  Sylvius.  It  is  on  the 
side  of  the  cerebrum  and  runs  backward  and  upward  from 
a  point  under  the  skull  on  a  level  with  the  eyebrows.  Al- 
though the  edges  of  this  fissure  are  in  contact,  there  is  usu- 
ally a  considerable  hollow  below  the  surface,  and  its  sides 
and  bottom  have  a  considerable  area.  This  area  is  called 
the  island  of  Reil  and  is  usually  spoken  of  as  one  of  the  five 
lobes.  From  a  point  near  the  middle  of  the  Sylvian  fissure, 
a  second  prominent  fissure  extends  upward  and  a  little 
backward  to  the  median  fissure  and  often  shows  on  the  me- 
dian surface  of  the  hemispheres.  It  never  extends  quite  to 
the  fissure  of  Sylvius,  but  is  separated  from  it  by  a  fold  or 
gyre.  The  fissure  itself  is  the  central  fissure,  or  fissure  of 
Rolando.  The  central  fissure  marks  off  the  frontal  lobe 
from  the  parietal  behind  it,  and  the  Sylvian  fissure  separates 
the  frontal  and  parietal  from  the  temporal  lobes.  The 
parietal  lobe  is  bounded  at  the  back  by  the  occipital  lobe. 


62 


FUNDAMENTALS  OF  PSYCHOLOGY 


The  line  of  division  is  distinct  on  the  median  surface  of  the 
cerebrum,  the  so-called  parieto-occipital  fissure,  but  no 
boundary  is  to  be  noted  on  the  lateral  surface.  The  line 
of  demarcation  between  the  parietal  and  temporal  lobes 


Fig.  32.  —  Localization  of  cerebral  functions.  The  figure  above  shows  the  outer 
surface  of  the  right  hemisphere;  the  one  on  p.  63,  the  mesial  surface  of  the  left 
hemisphere.  In  both  figures  the  motor  areas  are  marked  by  horizontal  shading,  the 
sensory  by  vertical  shading,  while  the  associatory  areas  are  unshaded.  The  doubt- 
ful or  partially  sensory  and  motor  areas  are  dotted.  S  is  opposite  the  fissure  of 
Sylvius;  R,  above  the  fissure  of  Rolando.  On  the  mesial  surface  the  parieto-oc- 
cipital fissure  is  just  above  the  shaded  portion  marked  V;  M  is  above  the  motor 

is  a  line  continuing  the  Sylvian  fissure.  It  should  be  stated 
that  the  fissures  and  gyres  are  not  the  same  on  different 
brains.  The  Sylvian  fissure  can  be  recognized  in  every  case, 
the  central  fissure  in  practically  every  case,  but  the  others 
are  subject  to  considerable  variation.  The  five  lobes,  the 
frontal,  temporal,  parietal,  and  occipital,  together  with  the 
island  of  Reil,  are  the  parts  into  which   the   cerebrum  is 


LOBES   OF  THE   CEREBRUM 


63 


divided.  The  two  important  reference  lines  are  the  fissures 
of  Sylvius  and  Rolando.  They  can  all  be  made  out  in  the 
diagram  (Fig.  32). 

While  the  functions  of  the  cerebrum  stand  in  closest  con- 
nection with  thought  and  with  mental  op:)erations  in  general, 
the  development  of  a  knowledge  of  the  exact  connection 


area;  C,  above  the  cutaneous  and  kina^sthetic  area;  V  indicates  the  visual  area; 
0  is  below  the  olfactory  area.  The  auditory  area  is  just  below  the  fissure  of  Sylvius, 
above  H.  FA  designates  the  frontal,  PA,  the  parietal,  and  TA,  the  temporal  asso- 
ciation areas.  There  is  some  evidence  that  the  dotted  areas  about  the  sensory  and 
motor  areas  are  areas  in  which  particular  associations  are  formed  for  the  corre- 
sponding sense  or  movements.  (The  diagram  embodies  the  results  of  A.  W.  Camp- 
bell, but  has  been  modified  in  one  or  two  respects  to  agree  with  the  results  of  Flech- 
sig  and  Gushing.) 


between  the  parts  of  the.  cerebrum  and  mental  action  has 
been  a  matter  of  very  slow  growth.  The  phrenologists, 
Gall  and  Spurzheim,  began  it,  but  their  methods  were  very 
inaccurate  and  their  conclusions  so  much  mixed  with  specu- 
lation that  hardly  any  progress  was  made.  After  their  time, 
in  the  third  decade  of  the  last  century,  through  the  work  of 


64  FUNDAMENTALS   OF  PSYCHOLOGY 

Flourens,  the  opinion  became  fully  established  that  the 
cerebrum  acted  as  a  unit,  and  no  function  could  be  assigned 
to  one  part  rather  than  another.  It  was  not  until  1867  that 
Broca's  studies  of  aphasia  gave  a  suggestion  that  each  part 
of  the  cortex  has  a  special  function,  and  led  to  studies  of 
localization.  Since  1890  the  localization  has  been  generally 
accepted.  The  only  problem  has  been  to  determine  how 
far  the  different  parts  interact  in  a  given  function. 

Methods  of  Studying  Localization  of  Function.  —  The 
methods  that  have  thrown  Hght  upon  the  subject  fall  in 
general  under  three  heads,  —  experiment,  observation  of 
the  effects  of  disease,  and  study  of  the  paths  and  anatomical 
structure  of  the  different  regions.  Experiments  were  early 
performed  on  the  lower  animals,  in  particular  upon  monkeys 
and  apes,  whose  brains  most  nearly  approach  those  of  man 
in  structure.  Parts  of  the  brain  were  extirpated,  and  when 
the  animal  had  recovered  from  the  shock  of  the  operation, 
its  movements  were  studied  to  see  what  change  the  opera- 
tion had  made.  Again  the  brains  of  animals  were  exposed 
and  the  cortex  stimulated  by  electric  currents  and  the  re- 
sulting movements  were  noted.  In  man,  cases  of  mental 
defects,  whether  sensory  or  motor  in  character,  were 
studied  carefully  and  then  the  brain  of  the  patient  examined 
after  death  and  the  two  series  of  results  b;-ought  into  con- 
nection with  each  other.  It  was  found,  for  example,  that 
a  man  who  showed  one  sort  of  difficulty  in  speech  would 
have  lesions  in  one  part  of  the  brain,  a  man  with  another 
sort  of  defect  would  have  another  area  diseased.  Careful 
study  of  many  cases  has  shown  that  there  is  a  close  relation 
between  the  two.  The  anatomical  methods  have  resulted 
in  tracing  paths  of  connection  between  many  areas,  and 
have  shown  some  relations  that  could  not  be  demonstrated 
by  either  of  the  others.    One  method  of  this  character  that 


THE   MOTOR  AREAS  65 

has  given  noteworthy  results  was  introduced  by  Flechsig. 
He  found  that  the  different  connecting  paths  in  the  brain 
became  medulhited  successively  as  the  nervous  system 
developed,  and  by  a  method  of  staining  brains  at  different 
ages,  he  was  able  to  make  one  path  stand  out  clearly  among 
all  of  the  others  and  to  follow  its  connections  with  ease  and 
certainty.  Even  more  recently  study  of  the  cells,  and  of  the 
arrangement  of  cells  and  fibres  that  make  up  different  areas, 
has  shown  that  areas  which  differ  in  function  differ  also  in 
their  finer  structure. 

As  a  result  of  these  methods,  we  feel  assured  that  the 
cortex  is  the  part  in  which  the  final  coordinations  take 
place  and  which  is  most  closely  related  to  consciousness. 
We  may  also  assert  that  the  cortex  constitutes  part  of  one 
of  the  paths,  by  which  sensations  may  be  brought  into 
connections  with  movements.  Since  the  brain  makes  pos- 
sible movement  when  a  sense  organ  is  stimulated,  certain 
parts  of  the  cortex  must  receive  axones  of  sensory  neurones, 
others  must  send  axones  down  to  the  muscles.  Fibres  have 
been  traced  to  the  cerebrum  from  sense  organs,  and  from 
the  cerebrum  to  the  motor  cells,  and  so  to  the  muscles. 
The  first  problem  is  to  determine  these  sensory  and  motor 
areas.  One  may  picture  the  sense  organs  and  muscles  as 
projected  upon  the  cortex.  The  areas  that  receive  sensory 
excitations  and  send  out  motor  impulses  are  known  as  the 
projection  areas.  Other  areas  have  been  shown  to  be  con- 
nected with  these,  to  have  fibres  leading  to  and  from  pro- 
jection areas.    These  are  known  as  association  areas. 

The  Motor  Areas.  —  The  motor  areas  are  most  definitely 
determined.  They  are  in  the  frontal  lobe  just  in  front  of 
the  central  fissure,  extending  from  near  the  fissure  of  Sylvius 
upward  to  the  median  fissure  and  over  on  to  the  median 
surface.    The  muscles  of  the  head  and  face  are  representee/ 


66  FUNDAMENTALS   OF  PSYCHOLOGY 

upon  the  lower  portion,  the  areas  for  the  arms,  the  legs,  and 
the  trunk  are  found  in  order  as  one  proceeds  upward. 
Since  the  descending  fibres  cross,  the  right  half  of  the  body- 
is  controlled  from  the  left  brain,  and  vice  versa.  The  details 
can  be  made  out  with  greater  accuracy  from  the  diagram 
than  from  any  description.  Some  of  the  movements  can  be 
locaHzed  with  great  definiteness.  The  thumb  has  a  separate 
area  for  the  control  of  its  movement,  and  the  same  may  be 
said  of  other  important  organs  and  muscles.  These  areas 
have  been  determined,  in  part  by  a  study  of  the  paralysis 
that  comes  with  disease  and  in  part  by  noting  the  move- 
ments that  result  from  stimulating  different  portions  of 
the  motor  cortex  in  animals.  Then,  too,  in  the  motor  areas 
are  certain  pecuHar  cells,  the  giant  pyramidal  cells,  whose 
axones  can  be  traced  down  the  brain  stem  and  cord  as  the 
pyramidal  tracts.  Most  important  of  all  is  the  fact  that  it 
is  possible  to  stimulate  the  motor  cortex  of  a  man  whose 
skull  has  been  opened  for  examination.  In  a  very  striking 
operation  by  Dr.  Gushing,  the  skull  was  opened  over  a  large 
area  during  primary  anaesthesia,  then  the  patient  was 
permitted  to  return  to  consciousness  and  the  cortex  stimu- 
lated while  he  was  in  a  condition  to  report  on  what  hap- 
pened. The  results  obtained  in  this  way  were  sufhcient  to 
convince  the  world  of  science  that  the  motor  part  of  the 
cortex  is  restricted  to  the  frontal  lobe  rather  than  extending 
backward  across  the  central  fissure,  as  was  thought  a  few 
years  before. 

The  Sensory  Areas.  —  The  sensory  areas  are  widely  dis- 
tributed. The  area  for  touch  is  found  in  the  parietal  lobe 
just  behind  the  central  fissure.  The  definite  localization  of 
parts  of  the  body  has  not  been  determined  as  it  has  for 
movement.  In  fact,  the  opinion  is  still  held  in  certain 
quarters   that  movement  sensations  alone  —  impressions 


THE   SENSORY  AREAS  67 

received  from  sense  organs  in  muscle  and  tendon  —  have 
their  seat  in  this  region,  while  the  skin  senses  proper  are 
found  elsewhere,  but  the  upholders  of  this  theory  assign 
them  to  no  definite  place.  Tracing  paths  and  observation 
of  injuries  both  coincide  in  giving  this  area  to  touch,  what- 
ever the  final  definition  of  that  term  may  be.  The  auditory 
area  has  been  located  in  the  posterior  portion  of  the  tem- 
poral lobe,  in  the  convolution  adjoining  the  fissure  of  Syl- 
vius, and  probably  extending  over  upon  the  wall  of  that 
fissure,  the  Island  of  Reil.  Even  more  accurately  deter- 
mined is  the  region  for  vision.  This  is  found  primarily  in 
the  calcarine  fissure  on  the  occipital  portion  of  the  median 
surface  of  the  hemispheres.  It  has  been  located,  on  the 
basis  of  examination  of  the  brains  of  cases  of  cerebral  blind- 
ness, by  tracing  fibres  from  the  optic  tracts  to  it,  and  by 
examination  of  the  brains  of  individuals  bUnd  from  birth 
or  early  childhood.  Donaldson  found,  for  example,  that 
the  brain  of  Laura  Bridgman  was  quite  undeveloped  in  this 
region.  The  partial  crossing  of  the  fibres  between  the  eye 
and  the  brain  has  been  very  definitely  made  out.  If  the 
right  occipital  lobe  has  been  injured,  the  patient  is  found 
to  be  blind  in  the  right  half  of  both  retinas,  while  the  left 
halves  retain  their  vision.  Each  fovea,  or  central  point  of 
clearest  vision,  seems  to  be  represented  on  both  hemispheres. 
Apparently,  too,  the  posterior  part  of  this  area  for  vision 
receives  impressions  from  the  lower  parts  of  the  retinas, 
while  the  anterior  portion  receives  its  fibres  from  the  upper 
retinas.  Smell,  and  particularly  taste,  are  least  well 
localized.  This  is  primarily  due  to  the  fact  that  a  patient 
may  suffer  from  considerable  defects  in  either  sense  without 
great  inconvenience,  and  in  consequence  is  less  Hkely  to 
complain  and  be  carefully  studied.  Paths  have  been 
traced,  however,  from  the  olfactory  nerve  to  the  extreme 


68  FUNDAMENTALS   OF  PSYCHOLOGY 

tip  of  the  temporal  lobe,  the  hippocamp.  This  region,  too, 
is  the  analogue  of  the  portion  of  the  cerebrum  that  is  well 
developed  in  the  lower  forms  that  show  greater  capacity 
for  smell,  so  that  all  that  we  know  points  to  it  as  the  cortical 
seat  of  the  olfactory  sense.  Taste  is  supposed  to  be  some- 
where in  the  same  region,  but  the  evidence  is  even  less 
certain  than  for  smell.  Each  of  these  areas  can  be  better 
made  out  from  the  diagram  (Fig.  32)  than  from  verbal 
statement. 

While  the  restricted  areas  described  above  are  probably 
the  more  immediate  sensory  receiving  stations  in  the  cortex, 
it  is  not  to  be  assumed  that  they  are  the  only  areas  con- 
cerned. We  have  evidence  that  about  both  visual  and 
auditory  areas  are  regions  that  have  a  related  function. 
Injuries  in  the  temporal  lobe  near  the  primary  auditory 
centre  tend  to  decrease  the  efficiency  of  hearing.  Lesions 
of  the  occipital  lobe  near  the  primary  visual  areas  give  rise 
to  partial  bUndness  or  inability  to  interpret  or  perceive 
objects.  These  regions  may  be  assumed  to  be  active  in 
connecting  and  elaborating  the  impressions  received  from 
the  sense  in  question,  rather  than  serving  as  the  primary 
receiving  centers. 

Association  Areas.  —  As  will  be  seen  from  the  diagrams, 
these  projection  areas,  taken  even  in  the  wider  sense  of  the 
last  paragraph,  include  relatively  small  portions  of  the  total 
area  of  the  hemispheres.  It  was  long  a  question  what  the 
functions  of  the  other  regions  might  be.  Flechsig  may  be 
said  to  have  found  the  answer.  By  his  method  of  tracing 
the  course  of  developing  nerve  tracts,  he  showed  that  masses 
of  fibres  led  from  the  projection  areas  to  the  other  regions 
of  the  brain,  —  that  some  were  connected  with  few,  some 
with  many  of  these  regions.  He  inferred  from  this  that  all 
of  the  cortex  not  included  in  the  projection  areas  serves  in 


FUNCTIONS  OF  THE  FRONTAL  LOBES   69 

association.  He  even  attempted  to  assign  specific  associa- 
tory  functions  to  different  areas.  The  posterior  portions  of 
the  parietal  and  temporal  lobes  and  parts  of  the  occipi- 
tal lobe  he  called  the  parieto-occipital  association  areas, 
and  he  assumed  them  to  have  the  function  of  forming  con- 
nections between  the  neighboring  sense  areas,  and  to  be 
the  seat  of  such  associatory  functions  as  those  involved  in 
the  perception  of  space.  The  frontal  lobe,  so  far  as  it  is  not 
included  in  the  motor  area,  he  makes  the  seat  of  the  more 
compKcated  associations  involved  in  reason  and  judgment. 
While  the  specific  functions  of  different  regions  cannot  be 
said  to  be  matters  of  agreement,  it  is  safe  to  hold  that  the 
general  function  of  the  silent  areas  is  to  make  possible  wide 
and  greatly  varied  associations  between  the  projection 
areas.  There  are  formed  the  innumerable  connections 
between  different  sensory  processes  and  between  sensory 
processes  and  movements  so  important  for  our  daily  life. 

Functions  of  the  Frontal  Lobes.  —  Specific  evidence  of 
the  dependence  of  associations  upon  the  frontal  lobes  was 
obtained  by  Franz  in  experiments  on  cats  and  apes.  When 
he  taught  his  animals  to  make  certain  responses  to  given 
stimuH,  and  then  removed  part  of  the  frontal  lobes,  the 
recently  formed  associations  were  destroyed,  but  an  act 
that  had  been  well  learned  was  not  disturbed  by  the  opera- 
tion. Animals  that  had  been  operated  upon  and  had 
recovered,  could  learn  new  movements,  and  these  were  again 
destroyed  by  a  second  operation.  It  might  be  argued  that 
the  results  noted  were  due,  not  to  removal  of  a  particular 
area  of  the  brain,  but  to  the  shock  or  other  general  effects 
of  the  operation.  To  obviate  this  objection  Franz  removed 
other  parts  of  the  brain  in  control  animals  and  found  that 
the  operation  was  without  effect  upon  retention.  He 
beUeves  that  his  results  have  estabUshed  the  close  connec- 


70  FUNDAMENTALS   OF  PSYCHOLOGY 

tion  of  the  frontal  lobes  with  associations.  Clinical  obser- 
vation in  general  supports  the  view  that  the  frontal  lobes 
are  important  association  regions  and  the  seat  of  compli- 
cated intellectual  operations.  When  these  are  injured,  the 
patient  is  usually  incapable  of  the  higher  mental  acts,  is 
said  to  lose  his  character,  to  be  reduced  to  idiocy  or  to  a  low 
mental  state.  On  the  other  hand,  considerable  portions 
of  the  frontal  lobe  may  be  lost  without  any  apparent  effect 
upon  the  individual.  Probably  the  two  sets  of  facts  are 
to  be  brought  into  harmony  on  the  assumption  that  any 
part  of  the  area  may  be  used  for  associations;  'after  asso- 
ciations have  been  formed  in  some  one  part  and  that  part 
is  removed,  the  knowledge  is  lost.  When  a  portion  is 
removed  in  which  no  connections  have  been  made,  no 
change  in  the  animal  can  be  noted.' 

Aphasia.  —  The  cooperation  of  the  various  areas  of  the 
cerebrum  in  mental  operations  can  be  well  illustrated  by  a 
study  of  the  facts  of  aphasia,  which  we  may  undertake  as 
a  final  review.  This  is  one  of  the  most  famiHar  defects, 
and  is  also  illuminating  because  speech  stands  in  such  close 
connection  with  all  of  the  other  mental  operations.  By 
aphasia  is  meant  the  loss  of  speech  due  to  any  lesion  of 
the  brain.  Two  forms  of  aphasia  are  ordinarily  distin- 
guished. One,  motor  aphasia,  is  characterized  by  inabihty 
to  produce  the  vocal  movements  in  a  coordinated  fashion, 
and  has  been  connected  since  Broca's  time  with  a  lesion  in 
the  third  frontal  convolution,  an  area  in  front  of  the  imme- 
diate motor  centres  for  the  muscles  of  the  head  and  throat. 
The  other  is  sensory  aphasia,  first  reported  by  Wernicke  in 
1874.  It  is  more  closely  connected  with  inabihty  to  hear, 
or  to  think  of  the  word,  a  word  deafness,  and  has  been 
shown  to  be  due  to  injury  of  the  auditory  centre  and  of  the 
immediately  contiguous  areas  of  the  temporal  lobes. 


PARTIAL  APHASIAS 


71 


Partial  Aphasias.  —  In  addition  to  the  cases  which  show 
complete  loss  of  function,  together  with  loss  of  capacity  to 
hear  or  to  anticipate  the  pronunciation  of  words,  one  must 
recognize  instances  in  which  the  patient  can  hear  mentally, 
can  reproduce  words  to  himself,  but  cannot  hear  when 
words  are  spoken.  On  the  other  hand,  there  are  patients 
who  can  recall  the  'feeUng'  of  words  as  they  are  spoken. 


Understandbip 
of  writing. 


Fig.  33.  —  Diagram  of  speech  areas.    (From  Bing,  op.  cil.) 

can  have  all  the  antecedents  of  speech,  but  cannot  speak. 
In  these  cases  lesions  have  been  found  in  the  subcortical 
regions  which  affect  the  projection  fibres  on  the  path  to 
the  muscles.  All  the  cortical  processes  go  on  as  usual,  but 
the  connections  with  sense  organ  and  with  muscles  are 
broken.  Other  distinctions  can  be  made  in  sensory  aphasia, 
in  particular  between  injury  of  the  primary  receiving  centre 
and  the  adjoining  elaborating  or  memory  areas.  Thus,  ac- 
cording to  Adolph  Meyer,  when  the  first  temporal  gyre  on 
the  side  next  the  island  is  injured,    'word-deafness'    re- 


72  FUNDAMENTALS   OF  PSYCHOLOGY 

suits.  In  case  the  lower  portion  of  the  gyre  is  injured,  on 
the  other  hand,  words  are  spoken  hit  or  miss,  what  is 
called  a  'word-salad'  is  frequent,  memory  for  words  seems 
disturbed  but  not  destroyed.  Still  another  element  must 
be  added  to  give  a  complete  picture.  Other  than  the  audi- 
tory memories  are  necessary  before  the  words  can  be  un- 
derstood in  their  completeness.  This  has  been  pictured  by 
Wernicke  and  others  as  a  process  of  connecting  the  word 
with  a  concept  in  a  concept  centre.  The  concept  centre  is 
probably  too  simple  a  way  of  disposing  of  the  process,  but 
it  is  necessary  to  connect  the  word  or  sound  with  a  large 
number  of  other  experiences  before  it  is  understood.  With 
suitable  reservations  this  may  be  interpreted  to  mean  that 
the  auditory  impression  makes  many  associations  before  it 
is  transferred  to  the  motor  centre.  If  these  connections 
are  impaired,  repetition  of  sounds  heard  is  possible,  but 
there  is  no  understanding  of  what  is  heard,  and  no  proper 
control  of  what  is  said. 

Five  operations  may  be  thought  of  as  necessary  for 
speech:  i,  the  reception  of  the  sound  in  the  primary 
centre  for  hearing;  2,  its  elaboration  in  the  association 
region  about  the  primary  centre;  3,  more  complete  elabo- 
ration by  reference  to  other  than  auditory  experiences 
(transfer  to  the  hypothetical  concept  centre);  4,  arousal 
of  the  coordinated  motor  impulses  in  Broca's  centre; 
5,  conduction  of  these  to  the  separate  motor  centres,  from 
which  the  impulses  are  sent  down  to  the  muscles.  The 
functions  of  areas  4  and  5  are  related  in  very  much  the 
same  way  that  a  higher  coordinating  region,  such  as  the 
cerebellum,  is  related  to  the  activity  of  a  mere  reflex  cen- 
tre. In  the  primary  motor  area,  a  single  muscle  or  muscle 
group  is  made  to  contract  by  stimulation;  in  the  Broca 
centre,  a  large  number  of  sensory  stimuli  are  coordinated 


PARTIAL  APHASIAS 


73 


and  distributed  to  each  of  the  different  motor  centres  to 
cause  just  the  right  amount  of  contraction  in  each  muscle 
at  just  the  right  time,  —  to  marshal  the  different  compo- 
nent movements  to  produce  a  satisfactory  total  result.  The 
disappearance  of  any  of  these  centres,  or  of  the  connections 


Centre  for 

—  —    muscles  of 

articulition. 


Fig.  34.  —  Showing  connections  broken  in  cortical  and  subcortical  motor  apha- 
sia. In  the  former,  i,  2,  and  3  are  interrupted;  in  the  latter  only  4.  (From  Bing, 
op.  cit.) 


between  them,  produces  aphasia,  or  in  less  serious  cases, 
paraphasia. 

Other  centres  that  have  been  connected  with  the  speech 
processes  are  the  reading  centre,  which  is  localized  on  the 
lateral  occipital  lobe,  and  the  writing  centre.  The  reading 
centre  has  the  same  relation  to  the  primary  visual  centre 
as  has  the  auditory  speech  centre  to  the  primary  auditory 
centre.    It  may  be  imagined  to  be  the  region  in  which  the 


74  FUNDAMENTALS   OF   PSYCHOLOGY 

visual  pictures  of  words  are  supplemented  with  memories 
and  thereby  understood.  When  the  centre  is  injured,  read- 
ing becomes  impossible  or  inaccurate.  The  writing  centre 
is  not  so  generally  accepted  now  as  it  was  a  decade  ago. 
There  have  been  a  few  cases  of  an  inability  to  write  with 
retention  of  abihty  to  speak,  but  it  is  assumed  that  these 
were  due  to  injury  below  the  cortex  or  to  paralysis  of  the 
arms  due  to  lesions  in  the  cortical  area  for  the  control  of 
arm  movements,  rather  than  to  the  destruction  of  a  single 
centre  for  the  coordination  of  the  specific  movements  in- 
volved in  writing,  similar  to  Broca's  centre  for  speech.  It 
should  be  said,  in  leaving  the  discussion  of  speech  func- 
tions, that  the  cases  are  by  no  means  so  clear  cut  as  one 
might  wish.  There  is  much  contradiction  and  confusion  in 
the  reports  of  cases  made  which  is  only  partially  harmonized 
in  such  a  schematism  as  that  given  above.  Still  this  may 
be  regarded  as  a  simple  picture  of  what  takes  place. 

The  Left  Cerebrum  Dominant.  —  It  should  be  empha- 
sized that,  in  right-handed  individuals  at  least,  the  speech 
functions  have  their  seat  in  one  hemisphere  mainly,  the 
left.  In  cases  of  injury  to  the  right  brain  in  what  corre- 
sponds to  Broca's  or  Wernicke's  centres,  speech  suffers 
Httle  injury.  Apparently  this  is  only  one  phase  of  the 
general  fact  that  in  right-handed  individuals  the  left  hemi- 
sphere cares  for  the  more  important  and  delicate  coor- 
dinations, while,  with  exceptions,  the  right  hemisphere 
dominates  in  the  left-handed  individuals.  If  an  injury  be 
done  to  the  right  hemisphere  in  the  third  frontal  convolu- 
tion but  the  primary  motor  centres  be  not  injured,  the 
speech  functions  are  not  disturbed.  Similarly,  when  the 
motor  region  in  the  left  hemisphere  is  injured  but  the  right 
is  unaffected,  it  is  found  that  the  left  hand  is  rendered  in- 
capable of  delicate  movements,  although  there  is  no  sign 


THE  LEFT  CEREBRUM  DOMINANT    75 

of  paralysis  and  the  coarser  movements  are  unaffected. 
Liepmann  found  one  case  in  which  both  hemispheres  were 
normal,  but  where  there  was  a  lesion  in  the  corpus  callo- 
sum,  the  mass  of  fibres  which  connects  one  cortex  with  the 
other  (Fig.  35).    In  this  case,  the  right  hand  was  normal, 


To  left  hand       '  ^  m^  NT^  ^     To  right  hand 

Fig.  3S.  —  Showing  the  lesions  that  might  break  the  connections  between  the 
left  and  right  hemispheres  and  so  produce  apraxia  of  the  left  hand.  If  the  lesion 
is  at  I,  the  right  hand  will  be  paralyzed  as  well;  if  at  2  or  3  only  apraxia  of  the 
left  hand  is  caused.    (From  Bing,  op.  cit.) 

the  left  what  is  called  apraxic,  —  that  is,  delicate  move- 
ments could  not  be  carried  through  with  accuracy.  These 
cases  indicate  that  the  highest  coordinations,  whether  in 
speech  or  in  manual  exercises,  are  accompKshed  in  the  left 
hemisphere.  It  has  been  suggested  that  right-handedness 
is  really  left-brainedness,  and  vice  versa. 


76  FUNDAMENTALS   OF  PSYCHOLOGY 

Restitution  of  Function.  —  Interesting,  too,  in  this  con- 
nection is  the  fact  of  restitution  of  function  in  cases  of 
cerebral  lesions.  Not  infrequently  an  aphasic  will  show 
marked  improvement,  sometimes  almost  complete  recov- 
ery, with  no  betterment  of  the  lesion.  In  surgical  cases 
the  patient  will  frequently  show  considerable  paralysis  im- 
mediately after  part  of  the  cortex  has  been  removed,  but 
with  the  passage  of  time  his  movements  will  become  nor- 
mal again.  Various  speculations  have  been  indulged  in  to 
explain  this  phenomenon,  such  as  that  the  function  is  taken 
over  by  the  other  hemisphere,  that  the  paralysis  is  due  to 
shock,  and  when  that  passes,  the  old  structures  regain  their 
activities,  or  in  general  that  some  other  part  of  the  nervous 
system  can  take  over  the  work.  No  one  of  these  theories 
has  received  general  acceptance,  nor  can  any  be  said  to  be 
altogether  satisfactory,  but  it  is  important  in  several  con- 
nections to  note  that  there  is  a  considerable  degree  of  flexi- 
bility in  function  exhibited  by  many  of  the  nervous  struc- 
tures. Surgeons  have  joined  part  of  the  central  end  of  a 
flexor  nerve  to  the  peripheral  end  of  an  injured  extensor 
nerve  and,  when  regeneration  has  taken  place,  the  nerve 
and  its  central  connections  perform  the  new  function  with- 
out a  hitch.  In  cases  of  destruction  of  paths  through  the 
cord,  as  in  infantile  paralysis,  it  is  found  that  other  paths 
will  be  substituted  and  the  paralysis  disappear  in  time, 
provided  only  that  the  muscle  be  kept  from  degenerating 
while  new  paths  are  being  developed.  Vicarious  func- 
tioning, replacing  of  one  structure  by  others,  seems  to 
be  a  fairly  general  law  of  nervous  action,  although  much 
remains  to  be  learned  of  the  Umits  and  details  of  the 
process. 

Resume  of  Nervous  Functions.  —  In  brief,  then,  we  see 
that  in  the  nervous  system,  the  action  of  all  parts  depends 


THE   ACTION   OF   THE   SYNAPSE  77 

upon  a  transfer  of  sensory  impulse  to  motor  neurones,  and 
the  consequent  excitation  of  muscular  movements.  There 
are  three  levels  in  the  nervous  system  at  which  the  transfer 
from  sensory  to  motor  organs  may  take  place:  i,  at  the 
level  of  the  simple  reflex  in  the  cord  or  brain  stem;  2,  in 
the  higher  coordination  centres  in  the  brain  stem,  the  cere- 
bellum, and  the  corpora  quadrigemina;  and  3,  in  the  cor- 
tex. As  one  passes  to  the  higher  levels,  the  number  of  sen- 
sory impulses  concerned  in  guiding  movements  becomes 
greater,  and  in  consequence  the  movements  become  more 
accurately  adjusted  to  the  environment,  to  the  circum- 
stances of  the  moment.  In  the  cortex,  the  association  cen- 
tres provide  regions  where  all  sense  impressions  may  be 
brought  into  connection  with  each  other  and  with  retained 
impressions,  and  where  all  combine  to  control  movements. 
Action  is  in  the  light  of  past  as  well  as  of  present  experi- 
ence. In  consequence,  the  highest  forms  of  adaptation  are 
possible.  Aside,  however,  from  the  increasing  complexity 
of  interaction,  the  highest  and  the  lowest  forms  of  nervous 
action  follow  the  same  laws.  The  control  of  the  path  taken 
by  the  impulses  through  its  structures  may  also  be  ex- 
plained on  the  same  general  principles. 

The  Synapse 

The  Action  of  the  Synapse.  —  Perhaps  the  best  notion 
of  these  principles  is  given  by  a  theory  elaborated  by  Pro- 
fessor Sherrington.  This  regards  the  course  of  an  impres- 
sion through  the  nervous  system  as  determined  by  the  ease 
or  difhculty  with  which  nerve  processes  may  pass  from  one 
neurone  or  nerve  element  to  another,  the  amount  of  re- 
sistance at  the  synapses.  This  has  already  been  briefly 
mentioned  in  the  prececHng  chapter.  The  great  number  of 
synapses  that  may  be  crossed  can  be  seen  in  Figure  36, 


78 


FUNDAMENTALS   OF  PSYCHOLOGY 


which   shows   the   large   number   of   collaterals   and   end 
brushes  of  a  single  neurone  from  the  cerebellum  of  a  rat. 

The  final  explanation  of  why  one  synapse  should  be 
more  permeable  than  another,  and  why  the  same  synapse 
should  be  more  easily  crossed  at  one  time  than  at  another, 
has  been  the  subject  of  much  discussion  and  is  not  com- 
pletely agreed  upon  as  yet.  The  earUest  and  simplest  ex- 
planation grew  out  of  the  picture  of  the  nervous  system  as 


Fig.  36.  —  The  numerous  points  of  connection  of  a  neurone  from  the  cerebellum  of 
a  rat.    (Cajal.) 

a  colony  of  individual  cells,  each  like  an  amoeba,  which 
could  control  in  some  degree  the  extension  and  withdraw- 
ing of  processes.  Just  as  a  group  of  amoebae  that  hap- 
pened to  be  in  contact  might  send  out  pseudopods  and 
touch  each  other  at  different  times  and  places,  so  the  neu- 
rones might  on  occasion  send  out  or  increase  the  length  of 
the  dendrites  until  they  came  into  contact  with  the  end 
brushes  of  the  neighboring  axones.  It  was  further  assumed 
that  when  physical  contact  was  present  between  the  neu- 
rones, a  nervous  impulse  might  pass,  while  at  other  times 
the  path  was  blocked.    Some  authorities  asserted  that  the 


THE   ACTION   OF   THE   SYNAPSE  79 

dendrites  were  shorter  in  animals  killed  by  an  anaesthetic 
than  in  others.  The  theory  was  used  to  explain  sleep  as 
due  to  a  blocking  of  all  the  pathways  to  consciousness. 
Later  consideration  has  led  to  the  abandonment  of  the 
theory.  It  would  make  all  action  of  the  nervous  system 
depend  upon  chance  activities  or  arbitrary  activities  in  the 
separate  cells,  rather  than  upon  the  way  they  were  affected 
from  without,  or  by  other  cells.  Sleep  might  be  satisfac- 
torily explained,  but  on  this  theory  it  would  never  be  pos- 
sible to  waken  the  individual  until  his  neurones  were  ready 
to  put  out  their  dendrites  again. 

Sherrington  is  convinced  from  a  careful  study  of  the 
times  required  for  the  reflex  movements  under  different 
conditions,  that  we  must  think  of  the  nervous  structure  as 
continuous.  A  membrane  at  the  synapse,  probably  analo- 
gous to  the  membrane  of  a  cell,  offers  a  resistance  to  the 
passage  of  the  impulse.  The  degree  of  resistance  is  de- 
termined by  the  degree  of  permeability  of  the  membrane. 
The  neurones  would  always  be  in  contact,  the  reflex  path 
is  always  continuous,  but  the  impulse  is  impeded  at  the 
point  of  contact  between  axone  and  dendrite. 

If  we  may  be  satisfied  with  the  theory,  we  still  have  to 
ask  why  one  synapse  should  be  more  permeable  than  an- 
other. In  the  lower  centres  it  may  be  assumed  that  the 
openness  of  certain  synapses  and  the  closed  condition  of 
others  is  inherited,  that  it  either  is  present  at  birth  or  ap- 
pears soon  after  as  a  result  of  the  inherited  predisposition. 
Few  reflexes  are  perfect  at  first,  —  they  improve  for  days 
or  even  weeks  in  the  higher  animals.  At  first  the  child 
does  not  accurately  touch  a  point  stimulated,  although 
there  is  usually  some  indefinite  waving  of  the  arms.  Many 
of  the  more  compKcated  reflexes  and  instincts  make  their 
appearance  late,  although  probably  the  development  comes 


8o  FUNDAMENTALS  OF  PSYCHOLOGY 

in  large  part  as  a  result  of  growth  rather  than  of  learning. 
The  paths  open  at  birth  determine  a  relatively  larger  pro- 
portion of  the  total  number  of  paths  in  the  cord  and  mid- 
brain than  in  the  cortex,  but  probably  form  a  large  number 
of  the  total  connections  even  in  the  adult  cortex.  The  gen- 
eral lines  of  connection  are  pretty  well  laid  down  even  there. 
Habit  a  Change  in  the  Synapse.  —  The  connections  that 
develop  in  the  Hfe  of  the  individual  as  a  result  of  learning 
are  due  to  changes  that  take  place  in  the  character  of  the 
synapse.  What  this  change  is  is  not  determined  and  can- 
not be,  so  long  as  we  do  not  know  what  the  nature  of  the 
opposition  in  the  membrane  may  be.  We  do  know  that 
the  more  often  two  neurones  are  excited  together  or  in 
immediate  succession,  the  greater  is  the  HkeKhood  that  the 
activity  of  one  will  extend  to  the  other.  All  learning, 
whether  in  the  formation  of  habits  or  in  the  connection  of 
sensory  impressions  in  sensory  learning,  is  due  to  this  re- 
duced resistance.  The  laws  that  govern  the  reduction  of 
resistance  from  use  are  known  in  some  degree  from  the  ob- 
servations of  the  behavior  of  the  organism,  but  our  theory 
takes  us  only  to  the  point  where  we  may  say  that  learning 
is  due  to  some  sort  of  reduction  in  the  resistance  offered  by 
the  synapse  to  the  passage  of  the  nervous  impulse. 

Our  picture  of  the  action  of  the  cortex,  as  of  the  cord,  is 
that  all  is  determined  by  the  openness  of  paths,  by  the 
synapses.  The  passage  of  the  impulse  from  sense  organ  to 
muscle  is,  as  has  been  emphasized  repeatedly,  the  expla- 
nation of  all  function,  whether  in  cord  or  in  cerebrum.  The 
difference  between  the  two  is  that  there  are  more  open 
paths  in  the  latter  over  wliich  any  impulse  may  pass  and 
that  for  the  most  part  these  paths  have  been  opened  by 
use,  by  the  earHer  activities  of  the  organism.  It  should 
also  be  emphasized  that  many  different  stimuh  cooperate 


FACILITATION  OF   IMPULSES  8i 

in  producing  the  activities  that  result  from  the  action  of 
the  cortex,  many  more  than  act  together  in  any  of  the 
lower  centres  or  organs.  The  cooperation  is  made  possi- 
ble by  the  fact  that  many  of  the  paths  have  common 
parts;  in  fact,  that  the  motor  part  of  the  path  is  common 
to  very  many  different  acts.  In  the  majority  of  cases  the 
same  muscles,  and  even  the  same  groups  of  muscles,  are 
used.  The  excitation  of  the  motor  path  may  be  aroused 
by  a  number  of  sensory  impressions,  and  the  various  im- 
pressions may  be  thought  of  as  cooperating  in  the  final 
action.  What  is  even  more  important  in  this  connection  is 
that  each  sensory  impression  may  be  connected  with  sev- 
eral motor  or  intermediate  neurones,  and  the  action  which 
results  when  the  sensory  impression  is  received  must  de- 
pend upon  the  openness  of  the  various  synapses,  of  paths 
leading  to  the  possible  motor  organs  that  may  be  excited. 
Where  very  large  numbers  of  stimuh  are  presenting  them- 
selves at  every  moment,  there  must  be  a  large  amount  of 
coordination,  of  reciprocal  influence,  to  determine  which 
of  the  possible  movements  is  actually  made.  The  strong- 
est impression  and  the  one  whose  neurone  has  the  most 
open  synapses  between  it  and  the  motor  neurones  will  de- 
termine the  action. 

Interactions  of  Impulses 

Facilitation  of  Impulses.  —  In  addition  to  this  mere 
openness  of  paths  and  the  greater  strength  of  the  impres- 
sions, coordination  seems  to  imply  mutual  interaction  be- 
tween the  neurones  of  one  path  and  those  of  another. 
Sherrington  and  others  have  demonstrated  two  forms  in 
which  one  path  or  series  of  neurones  may  act  upon  others. 
One,  the  more  direct,  is  some  process  of  making  easier  the 
path  for  one  response  by  another  set  of  neurones  active  at 


82  FUNDAMENTALS   OF  PSYCHOLOGY 

the  same  time.  This  is  very  common.  It  may  be  illus- 
trated very  easily  by  the  knee-jerk.  You  are  familiar  with 
the  fact  that  if  you  strike  sharply  the  tendon  below  the 
knee-cap  when  one  leg  is  crossed  over  the  other,  the  foot 
will  give  a  kick.  It  has  been  shown  that  the  kick  will  be 
much  stronger  if  the  hands  are  clenched  at  the  time  the 
blow  is  given.  The  clenching  of  itself  would  not  produce 
the  kick,  but  it  prepares  the  way  for,  or  facilitates,  the  re- 
sponse when  the  blow  is  given.  This  may  be  pictured  as  a 
preparatory  reduction  of  the  resistance  of  the  synapse 
which  makes  the  impulse  pass  more  easily,  and  hence  with 
greater  intensity,  when  the  suitable  stimulus  is  appHed. 

Inhibition  of  Impulses.  —  More  striking  is  the  second 
form  of  interaction,  inhibition.  Certain  paths  when  active 
prevent  the  action  of  others,  or  reduce  their  UabiHty  to  re- 
sponse. Sherrington  has  demonstrated  this  phenomenon 
in  the  case  of  many  reflexes,  such,  for  example,  as  the  gen- 
eral reduction  of  the  strength  of  the  reflexes  of  the  cord 
when  it  is  in  connection  with  the  cerebrum.  After  the  cere- 
brum has  been  removed  and  the  animal  has  recovered  from 
the  shock  of  the  operation,  all  reflexes  are  exaggerated,  a 
fact  explained  on  the  assumption  that  in  the  normal  animal 
all  lower  reflexes  are  inhibited  by  the  higher  centres.  More 
interesting  for  our  immediate  purpose  is  the  fact,  fully  es- 
tablished by  Sherrington  and  Hering,  that  the  flexor  and 
extensor  centres  in  the  cortex  mutually  inhibit  each  other. 
They  removed  the  flexor  muscles  of  a  member,  placed  the 
animal  in  such  a  position  that  there  was  a  tendency  for 
flexion,  —  it  was  supported  only  by  the  extensor  muscles, 
—  and  noted  that  the  member  was  lowered  when  the  flexor 
centre  was  stimulated.  This  they  explained  as  an  inhibi- 
tion of  the  cortical  centre  of  the  extensor  muscle  from  the 
flexor  centre  which  reduced  the  tonus  of  the  extensor,  and 


CONSCIOUSNESS   AND    CORTICAL   ACTION    83 

so  permitted  the  member  to  be  flexed.  This  was  also  dem- 
onstrated on  the  antagonistic  eye-muscles.  If  the  internal 
muscle  of  the  eye  were  severed  and  the  cortical  centre  for 
that  muscle  were  stimulated,  the  eye  would  turn  as  it  does 
upon  stimulation  of  that  centre  when  the  muscle  is  intact. 
This  mutual  checking  of  antagonistic  movements  prevents 
any  possibility  of  interference  between  groups  of  muscles 
in  voluntary  action.  It  makes  it  impossible  that  one  group 
of  muscles  should  pull  against  another.  Inhibition  is  -as- 
sumed by  Sherrington  to  be  due  to  the  action  of  one  set  of 
neurones  upon  a  synapse  somewhere  along  the  other  path 
of  discharge.  The  activity  of  that  set  of  neurones,  in  some 
way  as  yet  unknown,  makes  the  membrane  at  the  synapse 
much  less  permeable,  and  so  prevents  the  discharge  of  the 
impulse  across  it. 

These  processes  of  facilitation  and  inhibition  are  quite  as 
essential  to  the  interaction  of  various  stimuli  in  the  cortex 
as  in  the  lower  centres.  As  will  be  seen  from  time  to  time 
in  considering  the  mental  processes,  the  most  important 
and  striking  fact  is  the  wide  interaction  of  mental  pro- 
cesses. It  is  seldom  that  an  act  'or  a  thought  is  -controlled 
by  a  single  stimulus  alone  or  even  by  the  stimuli  that  are 
being  received  at  the  moment  of  action.  The  laws  of  .fa- 
cilitation and  inhibition  of  one  set  of  cortical  activities  by 
others  that  are  going  on  simultaneously  in  other  paths  and 
in  other  areas,  are  needed  if  we  are  to  obtain  any  accurate 
picture  of  cortical  action.  We  shall  have  occasion  to  recur 
to  these  interactions  in  our  explanations  of  mental  processes. 

Consciousness 

Consciousness  and  Cortical  Action.  —  The  relation  of 
consciousness  to  the  total  action  of  the  brain  may  be 
briefly  mentioned.    On  the  physical  side,  the  action  of  the 


84  FUNDAMENTALS   OF  PSYCHOLOGY 

nervous  system  may  be  thought  of  as  the  passage  of  chem- 
ical or  electrical  changes  or  processes  'through  its  various 
structures.  These  are  present  not  at  a  single  place  but 
everywhere  throughout  the  mass  of  neurones,  —  hundreds, 
if  not  thousands,  of  separate  sensori-motor  arcs  are  carry- 
ing impulses  at  the  same  time,  —  for  the  muscles  not  only 
are  moved  by  nerve  impulses  when  they  move,  but  are  also 
kept  in  slight  or  tonic  contraction  by  the  constant  action 
of  the  neurones.  But  of  all  these  activities,  only  relatively 
few,  perhaps  not  more  than  one  group  at  a  time,  are  ac- 
•companied  by  clear  consciousness.  The  others  do  their 
work  without  being  noticed.  If  they  contribute  at  all  to 
consciousness,  it  is  only  by  modifying  the  total  mass  in 
some  slight  degree.  They  are  silent  servants,  or  their 
addition  is  lost  in  the  complex.  The  general  rule  is  that 
consciousness  attaches  to  activities  which  are  performed 
for  the  first  time,  or  which  offer  special  difficulties.  As 
movements  are  repeated,  they  gradually  cease  to  attract 
attention,  and  usually  by  the  time  they  can  be  carried  out 
effectively,  only  the  intention  or  the  first  beginnings  of  the 
act  are  conscious.  There  is  *no  evidence,  however,  that 
the  impulse  follows  any  distinctively  new  path  after  it 
ceases  to  be  conscious,  that  a  voluntary  act  is  first  carried 
out  by  the  cortex,  for  example,  and  then  by  the  lower  cen- 
tres. It  seems  probable  rather  that  consciousness  drops 
away  as  the  impulse  crosses  the  synapses  more  easily. 
The  paths  followed  are  still  the  same  when  the  action  be- 
comes easy,  but  we  are  not  aware  of  the  activity. 

The  Autonomic  System 

The  Autonomic  Nervous  System.  • —  In  -addition  to  the 
central  or  cerebro-spinal  nervous  system  which  we  have 
outlined  above,  the  psychologist  must  also  mention  the 


THE   DUCTLESS    GLANDS  85 

so-called  autonomic  nervous  system.  The  autonomic  sys- 
tem as  a  whole  consists  of  a  number  of  ganglia,  whose 
function  is  to  receive  motor  impulses  from  the  cord  and 
brain  stem  and  distribute  them  to  the  viscera  and  glands 
that  they  excite.  As  compared  with  the  central  nervous 
system,  the  responses  are  very  slow  and  are  diffused 
throughout  several  organs,  rather  than  being  restricted  to 
isolated  groups  of  muscles.  These  ganglia  lie  on  both 
sides  of  the  spinal  column  in  the  central  trunk  and  in  the 
head  and  pelvic  region  are  found  near  the  organs  they 
excite.  They  all  receive  fibres  from  the  cranial  nerves  and 
spine.  Fibres  from  the  central  nervous  system  make  con- 
nections with  the  cell  bodies  of  the  autonomic  system,  and 
from  these  cell  bodies  non-medullated  fibres  extend  to  the 
organs  which  they  innervate.  They  are  distributors  of 
motor  impulses  from  the  central  nervous  system. 

Impulses  from  the  autonomic  system  extend  to  all  parts 
of  the  body.  They  cause  contraction  of  the  blood  vessels, 
erection  of  the  hairs  in  animals,  changes  in  the  size  of  the 
pupil,  secretions  of  the  glands,  including  the  sweat  glands, 
increased  rate  of  the  heart,  movements  of  the  walls  of  the 
intestines,  the  movements  of  excretion,  etc.  They  are  pre- 
eminent in  the  control  of  the  fundamental  bodily  mechan- 
isms. They  affect  consciousness  most  through  their  activ- 
ity in  emotions. 

The  Ductless  Glands  and  the  Activity  of  the 
Nervous  System 

The  Ductless  Glands.  —  A  series  of  organs  and  activi- 
ties which  need  to  be  taken  into  account  in  connection 
with  the  activity  of  the  nervous  system  and  which  depend 
upon  the  action  of  the  autonomic  system  has  been  discov- 
ered relatively  recently,  the  endocrine  or  ductless  glands. 


86  FUNDAMENTALS   OF  PSYCHOLOGY 

These  glands  secrete  certain  substances,  known  as  hor- 
mones, directly  into  the  blood.  These  hormones  are  essen- 
tial to  the  proper  functioning  of  the  nervous  system  in  par- 
ticular and  to  the  growth  of  many  other  parts.  The  Ust  of 
glands  which  influence  the  nervous  functions  includes  the 
thyroid  and  pituitary,  the  adrenal  glands  and  certain  parts 
of  the  sex  glands.  Possibly  we  should  include  also  the 
thymus  and  pineal  glands,  although  relatively  Uttle  is 
known  of  their  functions. 

The  Thyroid  Glands.  —  The  best  known  are  the  thyroid 
glands,  relatively  large  masses  in  the  front  part  of  the 
throat  (which,  when  abnormally  enlarged,  produce  goi- 
tres). The  secretions  of  the  thyroid  are  essential  to  the 
mental  life  and  to  the  proper  growth  of  brain.  A  cretin, 
who  is  an  individual  with  defective  thyroid  secretion,  is  of 
the  mental  level  of  a  child  of  four  or  five,  is  short  in  stat- 
ure, with  general  infantile  contours  of  the  body.  That  this 
is  due  altogether  to  lack  of  thyroid  secretion  is  shown  by 
the  fact  that  feeding  a  developing  child  thyroid  extract 
from  a  sheep  induces  a  marked  growth  and  increase  in  in- 
telHgence.  A  marked  cretin  at  two  years  may  be  a  nor- 
mal child  at  three.  The  treatment  must  be  begun  early  if 
it  is  to  be  effective,  and  the  improvement  will  continue 
only  so  long  as  the  treatment  is  kept  up.  Excess  of  thy- 
roid secretion,  on  the  other  hand,  induces  an  abnormal  ex- 
citabihty,  particularly  of  the  emotions.  Hyperthyroidism 
is  marked  by  excessive  pulse  rate,  by  wasting,  and  muscu- 
lar weakness,  and  by  great  irritabihty. 

The  Pituitary  Body.  —  The  pituitary  body  is  a  small 
protuberance  on  the  under  surface  of  the  brain  stem,  just 
back  of  the  optic  chiasma,  or  crossing  of  the  optic  nerve. 
It  is  connected  with  the  third  ventricle  by  a  hollow  tube. 
Three  parts  can  be  distinguished,  with  secretions  differing 


THE   DUCTLESS   GLANDS  87 

in  function.  The  anterior  portion  secretes  a  substance 
that  promotes  the  growth  of  the  body,  particularly  of  the 
bones  and  connective  tissues.  Cases  of  giantism,  asso- 
ciated with  mental  disturbances,  have  been  traced  to  ex- 
cessive secretions  of  this  anterior  lobe.  The  intermediate 
portion  secretes  a  substance  which  increases  the  contrac- 
tion of  unstriped  muscles,  and  another  substance  which 
probably  passes  directly  into  the  ventricles  of  the  brain 
and  is  essential  to  the  proper  functioning  of  the  cortical 
tissues.  Disturbances  of  this  secretion  result  in  a  marked 
decrease  in  inteUigence.  The  function  of  the  posterior  por- 
tion is  not  known. 

The  Adrenal  Glands. — The  adrenal  glands  are  small 
glands  near  the  kidneys,  which  have  connections  with  the 
sympathetic  nervous  system.  Excitation  of  the  fibres  in- 
nervating these  glands  induces  a  secretion  directly  into  the 
blood  that  increases  the  heart  rate,  changes  the  composi- 
tion of  the  blood,  and  causes  the  flow  of  glycogen  from  the 
liver.  This  adrenal  secretion  is  an  important  factor  in 
emotional  excitement  and  we  may  postpone  details  until 
we  consider  them  in  that  connection. 

Other  Glands.  —  It  has  been  suggested  that  the  pineal 
gland  may  have  a  similar  function,  possibly  to  inhibit  the 
effects  of  the  pituitary  secretion,  but  the  evidence  is  con- 
tradictory, and  we  must  await  further  evidence  before  we 
can  include  it  among  the  endocrine  glands.  The  same  may 
be  said  of  the  thymus. 

The  ductless  glands  as  a  whole  are  important  because 
they  secrete  substances  which  are  essential  to  the  growth 
of  the  nervous  system  and  to  its  proper  functioning.  For 
psychology,  they  have  an  interest  since  their  action  is  in- 
volved in  the  action  of  the  nervous  system,  and  more  par- 
ticularly since  in  emotional  reactions  they  influence  the 


88  FUNDAMENTALS   OF  PSYCHOLOGY 

responses  of  the  vital  organs  directly,  and  indirectly  they 
render  the  individual  more  susceptible  to  emotional  reac- 
tions. 

Body  and  Mind 

The  Relation  of  Body  and  Mind.  —  Much  of  modern 
psychology  since  Descartes  has  dealt  with  the  relation  of 
the  mental  processes  to  the  nervous  processes  which  we 
have  just  been  discussing.  The  problem  originated  from 
the  fact  that  behavior  may  be  studied  in  two  ways,  from 
without  and  from  within.  When  one  attempts  to  study 
man  with  the  scalpel  and  the  instruments  of  the  physiolo- 
gist, he  deals  always  with  the  physical  man,  with  nerve 
and  nerve  cell,  with  white  matter  and  gray  matter,  but  he 
never  finds  any  trace  of  sensation,  of  the  inner  experience. 
On  the  other  hand,  when  one  studies  the  mental  states 
and  devotes  oneself  to  what  can  be  seen  in  one's  own  con- 
sciousness, alone,  one  never  finds  any  immediate  e\'idence 
of  nerve  cells.  For  the  most  part  investigators  have  pre- 
ferred one  or  the  other  of  these  approaches  to  the  facts  of 
mind,  —  few  men  have  given  due  credit  to  both.  Even 
where  each  attracts  the  interest  of  the  same  man,  it  is  sel- 
dom that  both  are  combined  in  a  single  statement,  or  com- 
pletely harmonized.  More  frequently  one  is  entirely  sub- 
ordinated and  to  all  intents  and  purposes  we  are  given  an 
explanation  that  is  either  completely  materiaUstic  or  alto- 
gether spiritualistic.  Most  writers  compromise,  and  in 
subordinating  one  of  the  two  series  they  make  it  almost 
incidental,  without  real  force,  a  sort  of  ghost  of  mind  or  of 
body,  as  the  case  may  be,  which  merely  follows  the  activ- 
ity of  the  other  but  has  no  influence  upon  it. 

Very  generally,  at  present,  the  two  Unes  of  approach  are 
recognized  and  both  of  the  resulting  series  of  experiences 


THE   RELATION   OF   BODY  AND   MIND      89 

are  accepted  as  real.  The  most  troublesome  problem  is 
that  of  the  relation  between  them.  Two  theories  as  to 
this  relation  may  be  recognized.  One  takes  the  natural 
attitude  that  the  two  series  interact,  as  do  series  of  phys- 
ical events;  that  when  a  sense  impression  is  received,  it  is 
transmitted  to  the  brain  by  the  paths  we  have  indicated, 
and  that  in  the  brain  it  in  some  way  gives  rise  to  the  in- 
corporeal process  we  know  as  sensation  or  knowledge,  in 
the  same  way  that  the  vibration  of  a  sounding  body  may 
give  rise  to  vibrations  in  the  air.  Similarly,  it  is  assumed 
on  the  other  side  that  voluntary  processes  may  produce 
changes  in  the  nervous  system  and  so  in  the  physical  uni- 
verse, just  as  simply  as  do  physical  forces  in  other  physical 
objects.  This  theory  of  the  relation  of  body  and  mind  is 
known  as  interactionism. 

Another  theory  equally  current  at  present  is  known  as 
psychophysical  parallelism.  It  is  an  expression  of  the  con- 
servatism of  modern  thinkers  in  refusing  to  assert  any  par- 
ticular sort  of  relation  between  body  and  mind.  The  men- 
tal series  is  assumed  to  constitute  one  train  of  events  which 
can  be  explained  in  terms  of  earlier  mental  events;  the 
physical  series,  the  changes  in  nervous  elements,  is  made 
entirely  distinct,  and  it  is  assumed  that  it  can  be  completely 
explained  in  terms  of  the  antecedent  physiological  pro- 
cesses. The  relation  between  the  two  series  either  is  left 
unexplained  or  it  is  said  positively  that  there  is  no  in- 
teraction between  them.  In  recalling  an  event,  for  exam- 
ple, one  would  run  through  a  series  of  ideas  until  the 
proper  associate  presented  itself.  On  the  physical  side, 
the  series  in  recall  would  depend  upon  the  connections  that 
had  been  established  between  neurones  in  different  sensory 
areas  of  the  cortex,  and  the  action  resulting  from  the  recall 
would  be  due  to  the  transfer  of  some  nervous  excitation 


90  FUNDAMENTALS   OF  PSYCHOLOGY 

from  a  sensory  area  to  the  corresponding  motor  area. 
When  it  is  asked,  however,  how  it  happens  that  the  nerv- 
ous processes  are  always  accompanied  by  the  mental  states, 
one  of  two  answers  is  made.  The  more  extreme  men  as- 
sert that  there  is  no  present  connection  between  the  two 
series  of  events.  Each  runs  its  own  course  because  of 
some  of  the  antecedent  events  within  itself,  but  nothing 
that  happens  in  the  other  can  influence  it.  The  two  are 
kept  together  because  they  go  at  the  same  rate,  rather 
than  because  of  any  cross  connection  between  them.  Mem- 
bers of  the  other  school  are  less  dogmatic  in  the  negative. 
They  assert  merely  that  they  do  not  know  the  nature  of 
the  connection,  not  that  there  is  no  connection  between 
the  two  series. 

The  evidence  adduced  by  the  upholders  of  each  theory 
is  largely  negative.  The  negative  considerations  upon 
which  parallelism  is  based  are  the  fact  that  one  never  can 
appreciate  both  series  at  the  same  time,  can  see  nothing 
pass,  and  that  the  two  series  of  events  are  not  at  all  com- 
parable. One  cannot  think  of  a  thought  moving  a  stone, 
or,  in  CHfford's  term,  it  seems  absurd  to  assert  that  two 
cars  are  coupled  by  the  bond  of  affection  between  guide 
and  guard,  and  to  speak  of  a  thought  making  any  change 
in  nerve  cells  is  on  exactly  that  level.  At  times  the  argu- 
ment is  given  a  more  formal  turn  in  the  assertion  that  to 
assume  interaction  is  in  violation  of  the  doctrine  of  the 
conservation  of  energy.  If  the  physical  series  is  to  be  re- 
garded as  a  closed  system  of  energy,  it  can  neither  give  off 
energy  to  the  mental  states  as  is  required  if  sensations  are 
to  be  caused,  nor  can  it  be  changed  by  mental  states,  as 
would  be  necessary  if  human  volitions  were  to  exert  an  in- 
fluence upon  the  nerve  cells.  In  passing  upon  these  objec- 
tions, one  must  remember,  however,  that  the  doctrine  of 


THE   RELATION  OF   BODY  AND   MIND      91 

conservation  is  itself  only  a  principle  that  has  been  set  up 
for  convenience,  and  must  be  given  up  if  it  should  cease  to 
harmonize  with  facts,  and  also  that  it  may  be  possible  in 
the  future  to  include  the  mental  world  in  some  wider  sys- 
tem of  relations  in  which  the  mental  and  the  physical  shall 
be  brought  together.  The  objection  is  more  formal  than 
real.  We  come  back,  then,  to  the  original  assertion  that 
we  cannot  make  a  single  observation  that  will  include  a 
mental  event  and  the  physical  event  which  causes  it  or  is 
caused  by  it,  and  in  consequence  cannot  obtain  even  an 
approximate  picture  of  how  one  is  related  to  the  other. 
There  is  not  so  much  as  a  good  analogy  for  the  connection, 
and  most  explanations  are  analogies. 

On  the  other  hand,  the  interactionist  insists  with  great 
firmness  that  mere  failure  to  see  what  happens  when  two 
events  succeed  each  other  uniformly,  does  not  prove  that 
they  do  not  stand  in  some  active  relation,  even  in  causal 
relation  to  each  other.  It  is  very  seldom,  if  ever,  that  one 
is  actually  aware  that  some  force  has  passed  from  one  phys- 
ical object  to  another;  one  seldom  knows  anything  of  what 
has  taken  place  between  them.  The  ability  to  trace  energy 
relations  is  the  exception  rather  than  the  rule.  In  other 
words,  the  relation  between  the  mental  and  the  physical 
series  of  events  is  no  more  unknown  than  is  any  other  ac- 
tive relation.  There  is  therefore  no  more  objection  to  re- 
garding the  psychophysical  relation  as  causal  than  the 
relation  between  heating  and  expansion  or  any  other  sim- 
ple physical  relation.  Physical  cause  is  itself  not  under- 
stood, and,  if  one  goes  deep  enough,  is  as  much  a  mystery 
as  the  relation  of  mind  and  body.  While  one  may  grant 
all  this  very  readily,  it  does  not  necessarily  follow  that  to 
change  from  one  side  to  the  other  too  often  and  too  quickly 
—  to  introduce  mental  elements  into  the  physical  series 


92  FUNDAMENTALS   OF  PSYCHOLOGY 

and  physical  into  the  mental  series  —  may  not  give  rise  to 
vagueness  and  uncertainty.  As  a  matter  of  fact,  while  one 
may  admit  that  there  are  causal  interconnections  between 
nervous  system  and  mind,  it  is  also  true  that  many  argu- 
ments become  vague  if  the  speaker  jumps  from  one  series 
to  the  other  for  an  explanation.  While  we  shall  admit  that 
mind  and  body  undoubtedly  interact,  we  shall  endeavor  as 
far  as  possible  to  keep  the  explanation  of  physical  states  in 
terms  of  antecedent  physical  states,  and  the  explanation 
of  mental  states  in  terms  of  antecedent  mental  states,  and 
assume  as  little  interaction  between  the  series  as  is  possible. 
It  is  necessary  to  accept  an  effect  of  the  sense  organs  and 
sensory  neurones  upon  consciousness  to  understand  the 
material  of  consciousness  and  an  influence  of  voluntary 
processes  on  muscles  if  we  are  to  understand  action.  Aside 
from  these,  however,  clearness  demands  that  all  mixing  of 
the  two  sets  of  explanations  be  avoided. 

REFERENCES 

Bing:  Compendium  of  Regional  Diagnosis. 

Dunlap:   Outline  of  Psychobiology. 

Herrick:  Introduction  to  Neurology. 

Ladd-Woodworth:  Physiological  Psychology.    Pp.  13-293. 

Strong:  Why  the  Mind  has  a  Body. 

MacDougall:  Body  and  Mind. 

Starling:  Physiology,  Ch.  VII,  §§  xvii-xix. 

Schaeffer:  The  Endocrine  Glands. 

VON  MoNAKOW:  Die  Lokalisation  im  Grosshirn. 


CHAPTER  IV 

SENSATION 

General  Remarks 

We  have  seen  from  our  discussion  of  the  action  of  the 
nervous  system  that  all  nervous  action  starts  in  sensation 
and  leads  to  movement.  The  first  half  of  this  assertion  is 
to  be  our  guiding  principle  in  discussing  the  qualities  of 
consciousness.  All  the  materials  of  our  knowledge  are 
derived  from  sensation.  We  have  just  as  many  different 
sorts  of  consciousness  as  we  have  qualities  of  sensation,  and 
consciousness  persists  apparently  only  so  long  as  impres- 
sions are  playing  upon  our  sense  organs.  The  old  sensa- 
tionalists, Hobbes  and  Locke,  for  example,  insisted  that 
there  could  be  nothing  in  mind  that  had  not  previously  been 
in  sense.  While  we  do  not  to-day  accept  the  principle  quite 
so  Hterally  as  they  did,  yet  it  is  easy  to  see  that  the  funda- 
mental quahties  of  mind  are  derived  altogether  from  the 
external  senses.  One  can  imagine  no  color  or  sound  that 
has  not  at  some  time  been  seen  or  heard;  or,  to  put  it  more 
conservatively,  one  can  call  to  mind  no  quality  of  any  kind 
that  has  not  at  one  time  come  through  the  senses.  One 
caimot  picture  the  color  of  an  ultra-violet  light,  or  think 
what  it  would  be  hke  if  one  were  suddenly  to  develop  a 
sense  organ  that  might  be  affected  by  it,  nor  can  one  think 
how  the  magnet  might  affect  one  if  some  sense  organ  should 
be  developed  to  respond  to  it.  Memory,  imagination,  and 
reasoning  are  Hmited  in  the  quahties  that  they  make  use 
of  to  the  bare  materials  of  sense.  They  may  recombine 
9,? 


94  FUNDAMENTALS   OF  PSYCHOLOGY 

them,  they  may  make  use  of  the  sense  materials  in  new 
ways,  but  they  can  add  no  new  quahties. 

Classification  of  Sensations.  —  The  quahties  of  sensa- 
tion might  conceivably  depend  either  upon  the  nature  of 
the  stimulus  or  upon  the  nature  of  the  receiving  organ.  The 
popular  mind  accepts  the  former,  but  most  psychologists 
believe  that  they  are  determined  by  the  character  of  the 
sense  organ  or  the  connected  portions  of  the  nervous  system, 
by  the  nature  of  the  sensory  ends  that  are  turned  outward 
to  the  physical  world.  That  the  nature  of  the  sensation 
does  not  depend  altogether  upon  the  stimulus  is  evident 
from  the  fact  that  different  stimuH  produce  the  same  sensa- 
tion when  they  affect  the  same  sort  of  nerves.  Thus  we 
shall  see  that  menthol,  pressure,  and  heat  or  its  lack  all 
produce  the  sensation  of  cold  when  they  act  upon  a  cold 
spot  on  the  skin.  On  the  other  hand,  the  same  stimulus, 
an  electric  current,  for  example,  produces  a  different  sensa- 
tion as  it  acts  upon  different  kinds  of  sense  organs:  cold  on 
a  cold  spot,  Hght  on  the  retina,  etc.  These  facts  and  others 
seem  to  show  fairly  conclusively  that  the  nature  of  the 
sensation  is  determined  by  the  receiving  organ,  rather  than 
by  the  stimulus  that  is  applied;  by  the  character  of  the 
receiving  tissue  that  has  been  developed,  rather  than  by 
the  character  of  the  outside  world.  If  this  be  accepted 
provisionally,  it  furnishes  a  convenient  means  of  classifying 
sensations.  Could  one  but  determine  the  different  sorts  of 
sense  ends  that  come  to  the  surface  of  the  body  or  are  im- 
bedded in  its  substance,  one  would  also  have  a  complete 
Hst  of  the  possible  sensations.  In  practice  one  usually  dis- 
criminates the  sense  quahty  first  and  later  discovers  the 
sense  organ,  but  the  classification  nevertheless  is  assumed 
to  be  in  terms  of  the  sense  organ.  We  may  accept  for  the 
moment  the  general  principle  that  the  number  of  sense 


ATTRIBUTES   OF   SENSATION  95 

qualities  is  determined  by  the  number  of  sorts  of  sensory 
tissue  that  can  be  stimulated. 

The  classification  of  sensations  still  offers  some  difficulties, 
since  the  fundamental  kinds  of  sense  ends  must  be  grouped 
in  some  way  for  convenience  of  treatment.  In  certain  cases 
the  similar  nerves  are  combined  in  some  one  organ.  Thus 
in  the  eye  are  thousands  of  nerve  ends  stimulated  by  the 
same  physical  forces,  and  giving  rise  to  similar  sensations. 
In  the  skin,  on  the  other  hand,  four  kinds  of  sense  ends  are 
scattered  indifferently  over  the  surface,  and  while  we  com- 
monly speak  of  the  skin  as  the  sense  organ  of  touch,  there 
are  really  at  least  four  different  kinds  of  sensation  received 
from  the  skin.  Taste  and  smell  offer  an  inconsistency  of  the 
opposite  sort.  The  organs  are  distinct,  but  the  stimuli 
are  closely  similar  and  the  quahties  of  sensation  are  not 
discriminated  by  the  popular  mind,  yet  science  and  common 
sense  follow  the  organ  rather  than  the  quahty  in  making 
them  distinct  sense  departments.  One  may  say,  then,  that 
in  classifying  sense  qualities,  the  organ  provides  the  first 
means  of  grouping,  and  within  the  organ  the  subdivisions 
may  be  either  in  terms  of  the  classes  of  stimuli,  or  of  the 
quaUties  of  sensation,  or  of  both. 

Attributes  of  Sensation.  —  When  one  attempts  to  enu- 
merate all  possible  sorts  of  mental  quahties  or  sensations, 
one  sees  very  quickly  that  there  are  various  kinds  of  differ- 
ences that  are  not  on  exactly  the  same  level.  It  is  not 
possible  to  arrange  all  the  different  kinds  of  sensation  from 
any  organ  in  a  single  series,  the  members  of  which  differ 
from  each  other  in  one  respect  only.  Thus  in  the  case  of 
sound,  we  may  distinguish  differences  of  pitch  and  also 
differences  of  loudness.  These  vary  independently.  A  high 
tone  may  be  either  loud  or  faint.  These  different  ways  in 
which  sensations  may  vary  are  called  the  attributes  of  sen- 


96  FUNDAMENTALS   OF  PSYCHOLOGY 

sation.  How  many  attributes  there  are  is  by  no  means  a 
matter  of  agreement.  All  agree  that  one  must  distinguish 
differences  in  quality  from  the  differences  in  intensity.  The 
quaHty  may  be  said  roughly  to  depend  upon  the  specific 
character  of  the  sense  organ  stimulated,  while  the  intensity 
depends  upon  the  degree  to  which  the  organ  is  stimulated. 
There  are  exceptions  to  both  of  these  statements.  In  the 
case  of  Hght,  for  example,  the  strength  of  stimulus  in  part 
determines  the  organ  stimulated.  It  has  been  proved  that 
faint  lights  are  seen  by  one  set  of  organs,  bright  lights  by 
another.  In  the  eye,  too,  even  with  bright  lights,  variation  in 
physical  intensity  is  not  distinguished  from  change  in  quality 
of  excitation.  The  grays  correspond  to  changes  in  strength 
of  Hght,  but  the  untrained  observer  puts  them  on  the  same 
level  with  change  in  color.  Black,  white,  and  gray  are  popu- 
larly regarded  as  colors.  But  in  all  other  senses,  the  distinc- 
tion in  quahty  and  intensity  offers  little  difficulty,  and  these 
two  attributes  are  recognized  by  practically  all  psychologists. 
Extent  and  Duration.  —  More  difficult  it  is,  however, 
to  dispose  of  some  of  the  other  attributes  sometimes  ascribed 
to  sensations.  Thus  every  object  possesses  extent,  and 
every  event  occupies  time,  has  duration.  Many  authorities 
speak  of  extent  and  duration  as  attributes  of  sensation,  as 
fundamental  ways  in  which  sensations  may  vary.  In  the 
simplest  cases,  these  ways  of  varying  seem  immediate  and 
unanalyzable,  but  in  many  more  instances  it  is  possible  to 
show  that  the  appreciation  both  of  extent  and  of  duration 
depends  upon  more  complicated  mental  operations.  They 
belong  rather  to  the  object  than  to  the  sensation  as  such.  In 
consequence  it  is  more  convenient  to  treat  them  both  under 
the  head  of  perception,  as  a  process  of  mental  elaboration 
of  sensations,  rather  than  as  an  immediate  characteristic 
of  the  elementary  sensation.    Very  much  the  same  state- 


THE   STIMULI  FOR  VISION  97 

ment  may  be  made  of  clearness  and  feeling  tone,  regarded 
by  some  authorities  as  attributes.  It  is  at  least  a  question 
whether  feeling  is  not  entirely  independent  of  sensation  and 
an  equally  primary  mental  state.  Clearness  is  a  change 
induced  in  sensations  as  a  result  of  their  connections  in 
consciousness,  not  an  attribute  of  sensations  themselves. 
Whether  we  are  to  regard  them  as  irreducible  parts  of  sensa- 
tions, or  as  independent  elements,  or  as  accidents  of  the 
ways  of  receiving  the  sensation,  can  be  best  discussed  in  a 
later  chapter.  For  the  present  we  may  content  ourselves n. 
with  the  statement  that  sensations  vary  in  specific  quality 
which  depends  primarily  upon  the  nature  of  the  receiving 
end  organ,  secondarily  upon  the  character  of  the  stimulus; 
and  in  intensity,  which,  in  its  turn,  is  dependent  upon  the 
amount  of  stimulation  that  affects  the  sense  organ.  Con- 
sidering qualities  alone,  the  sensations  fall  into  certain 
series,  marked  by  continuous  change  in  some  one  respect. 
It  is  impossible,  however,  to  find  similar  continuous  changes 
from  series  to  series.  Thus  colors  vary  in  a  continuous 
series  of  hues;  sounds  show  a  continuous  series  of  pitches; 
but  there  is  no  gradation  from  sound  to  sight.  Through 
each  quality  runs  a  series  of  intensities  which  is  regularly 
graduated  from  zero  to  a  maximum.  We  shall  discuss  first 
the  quahties  in  their  dependence  upon  the  organ  and  the 
stimulus,  then  the  intensities. 

Vision 

The  Stimuli  for  Vision.  —  We  may  begin  with  the  most 
important,  if  one  of  the  most  complicated,  of  the  senses,  — 
vision.  The  physical  stimuH  for  sight  are  vibrations  in  the 
ether  ranging  from  some  400  to  800  mm'  in  length.  Helmholtz 

1  ixfj.  means  thousandths  of  a  thousandth  of  a  milUmetre.  This  is  usually 
expressed  as  X. 


98  FUNDAMENTALS   OF  PSYCHOLOGY 

under  favorable  circumstances  saw  rays  as  long  as  835  X 
and  as  short  as  318  X.  For  the  average  eye  under  normal 
conditions  the  values  range  from  760  X  to  397  X.  Between 
these  limits  lies  the  visible  spectrum  from  red  to  violet. 
We  give  names  to  different  qualities,  but  it  is  somewhat 
difficult  to  say  just  where  one  color  changes  into  another. 
The  physical  relations  have  Kttle  significance  for  the  quality 
of  the  sensation,  since  the  colors  do  not  change  in  the  same 
degree  as  the  wave  length  and  very  few  of  the  laws  of  color 
can  be  stated  in  terms  of  the  wave  lengths  of  light.  We 
must  turn  from  the  physical  to  the  physiological  for  an 
explanation  of  the  phenomena  that  interest  us.  For  this 
we  must  consider  the  essential  features  of  the  structure  of 
the  eye. 

The  Structure  of  the  Eye 

The  Eye  and  its  Appendages.  —  The  eye  is  a  part  of  the 
brain  that  has  come  to  the  surface  of  the  body  in  the  course 
of  its  development,  has  increased  the  primary  sensitiveness 
of  nerve  tissue  to  light  by  the  development  of  new  photo- 
chemical substances,  and  has  gained  a  system  of  lenses, 
grown  protective  coats,  and  acquired  a  mounting  that  per- 
mits of  ready  turning  in  all  directions.  The  eyes  are 
mounted  in  deep  conical  sockets  in  the  skull,  where  they  are 
well  protected.  The  eyeball  is  kept  in  its  place  in  the  socket 
by  the  capsule  of  Tenon,  a  pouch-shaped  membrane  that 
surrounds  the  posterior  three  fourths  of  the  eye-ball.  It 
contains  synovial  fluid  which  acts  as  a  lubricant  when  the 
eye-ball  turns.  The  muscles  in  its  tissue  also  contract  with 
the  ocular  muscles  and  prevent  them  from  drawing  the  eye 
back  into  the  socket.  To  prevent  foreign  particles  from 
entering  the  socket,  the  front  is  closed  by  the  conjunctiva, 
a  membrane  continuous  with  the  inner  lining  of  the  eyelids 


THE   STRUCTURE   OF  THE  EYE 


99 


and  the  outer  surface  of  the  eyeball.  The  padding  of  fat, 
the  conjunctiva,  and  the  capsule  of  Tenon,  hold  the  centre 
of  the  eye  fairly  well  fixed,  and  at  the  same  time  permit 
it  to  turn  easily  about  its  centre. 

The  Three  Coats  of  the  Eye.  —  The  eyeball  is  approxi- 
mately a  sphere,  a  little  less  than  an  inch  in  diameter  (23-24 
mm.).  The  spherical  shape  is  given  it  by  the  outer  or  scle- 
rotic coat,  which  is  kept  distended  by  the  fluids  within, 
submitted  to  constant  pressure  by  the  general  circulation. 
This  pressure  amounts  to  about  25  mm.  of  mercury  in  the 
normal  individual.  The  eyeball  has  three  principal  coats. 
The  sclerotic  is  a  tough  protective  coat  of  connective  tissue. 
Inside  the  sclerotic  is  the  choroid  coat,  made  up  mostly  of 
blood  vessels  with  some  muscles  and  nerve  fibres.  Still 
farther  within  is  the  retina,  the  nervous  structure  and  true 
sense  organ. 

Each  of  these  coats  shows  modifications  in  some  part. 
The  sclerotic  coat  in  the  front  of  the  eye  has  a  shorter  radius 
of  curvature,  is  transparent,  and  bulges  forward  as  a  part 
of  the  lens  system.  Here  it  is  called  the  cornea.  It  can  be 
seen  to  protrude  from  the  sclerotic  if  one  will  look  across 
the  eye  of  another.  Back  of  the  cornea  is  a  chamber 
filled  with  a  watery  fluid.  This  is  the  anterior  chamber, 
and  the  fluid,  the  aqueous  humor.  In  this  chamber  is  an 
extension  of  the  choroid  coat,  the  iris,  which  is  not  attached 
to  the  sclerotic  or  cornea,  but  extends  across  the  anterior 
chamber  in  the  aqueous  humor.  In  its  centre  is  a  hole,  the 
pupil.  The  iris  gives  the  color  that  is  regarded  popularly 
as  characteristic  of  the  eye.  In  the  dark  types,  black  or 
brown,  it  is  much  pigmented;  blue  and  gray  eyes  are  less 
pigmented.  The  size  of  the  pupil  is  determined  by  the  rela- 
tive degree  of  contraction  of  two  muscles  or  sets  of  muscles : 
(i)  a  muscle  with  radial  fibres,  the  dilator  of  the  pupil,  and 


loo        FUNDAMENTALS   OF  PSYCHOLOGY 

(2)  the  sphincter,  a  muscle  with  circular  fibres.  These  are 
controlled  reflexively  by  the  degree  of  stimulation  of  the 
optic  nerve.    The  course  of  the  reflex  in  constriction  was 


Fig.  37.  —  Section  of  the  eye;  Scler.,  sclerotic  coat;  Chor.,  choroid;  Ret.,  retina; 
Opt.,  optic  nerve;  Fov.  c,  fovea;  Pr.  cil.,  the  ciliary  muscle  or  ciliary  process;  Conj., 
conjunctiva;  Cam.  ant.,  the  anterior  chamber;  corpus  vitreum,  the  vitreous  humor 
that  fills  the  main  body  of  the  eye.    (From  Angell's  "Psychology.") 


traced  on  page  56.  Dilation  involves  a  reflex  through  a  long 
path  down  to  the  cord  and  back  through  the  cervical  sym- 
pathetic nerve  and  superior  sympathetic  ganglion  to  the 


THE  MECHANISM  OF  ACCOMMODATION     loi 

eye.  The  widespread  course  of  the  pupillary  reflex  makes 
it  very  important  in  the  diagnosis  of  nervous  diseases  in 
general.  It  is  affected  by  lesions  in  many  different  struc- 
tures. In  the  normal  individual,  the  constriction  takes 
place  promptly  on  increase  of  illumination,  while  dilation  is 
relatively  slow  because  of  the  long  course  through  the  sym- 
pathetic nerves.  The  function  is  in  part  protective  by 
reducing  strong  lights,  but  also  has  somewhat  the  effect  of 


FAR 


NEAR 


Fig.  38.  —  Change  in  lens  and  ciliary  muscle  in  accommodation.    Left  shows  accom- 
modation for  distant,  right,  for  near  objects.    (From  Foster's  "Physiology.") 

the  diaphragm  of  a  camera.  It  gives  better  definition  be- 
cause it  "stops  down"  the  pupil  when  the  Hght  is  strong 
enough  to  permit  and,  when  the  light  is  faint,  it  admits  more. 
Constriction  of  the  pupil  also  accompanies  accommodation 
to  near  objects. 

The  Mechanism  of  Accommodation.  —  Back  of  the  iris 
and  directly  against  it  is  the  lens,  the  most  important  of  the 
optical  mechanisms.  It  consists  of  a  large  number  of  layers. 
The  front  surface  of  the  lens  has  in  youth  a  natural  radius 
of  curvature  of  4.8  mm.;  the  posterior  surface,  of  4.6  mm. 
Ordinarily,  however,  it  is  held  flattened  by  the  strain  of 
the  suspensory  Ugament.     This  extends  from  the  ciliary 


•I02        FUNDAMENTALS   OF  PSYCHOLOGY 

processes  on  the  ciliary  muscle  to  the  edge  and  the  front  and 
back  surfaces  of  the  lens.  The  lens  with  its  attachments 
constitute  the  mechanism  of  accommodation.  It  makes 
possible  the  focussing  upon  objects  at  different  distances. 
The  active  agent  is  the  cihary  muscle.  It  is  attached  to 
the  sclerotic  coat  near  the  angle  formed  by  the  increasing 
curvature  of  the  cornea,  and  the  fibres  run  back  to  lose 
themselves  in  the  structure  of  the  choroid  coat.  The  sus- 
pensory ligament  -is  attached  to  the  side  of  the  muscle 
instead  of  the  end,  as  are  the  tendons  of  other  muscles, 
so  that  the  contraction  of  the  muscle  means  relaxation 
of  tension  on  the  suspensory  Kgament  rather  than  in- 
crease of  tension.  When  the  tension  of  the  suspensory 
ligament  is  released,  the  lens  resumes  its  normal  shape, 
owing  to  its  elasticity.  As  one  grows  older,  the  lens 
becomes  less  and  less  elastic,  and  accommodation  practi- 
cally disappears  between  45  and  55  years.  Back  of  the 
lens  is  the  large  main  chamber  of  the  eye,  filled  with  the 
vitreous  humor,  so  called  because  it  has  the  consistency  of 
molten  glass.  This  fills  the  cavity  between  the  retina  and 
the  lens. 

Dioptrics  of  the  Eye.  —  Regarded  as  an  optical  system, 
the  function  of  the  eye  is  to  project  an  image  of  an  object 
upon  the  retina.  The  important  refracting  surfaces  are 
three,  the  front  surface  of  the  cornea  and  the  front  and  back 
surfaces  of  the  lens.  The  indices  of  refraction  of  the  cornea, 
and  of  the  aqueous  and  vitreous  humors,  are  approximately 
identical,  and  each  is  approximately  the  same  as  that  of 
water,  —  i.337-  The  refractive  index  of  the  lens  in  practi- 
cal effect  is  1.437.  The  average  radius  of  curvature  of  the 
cornea  is  8  mm.,  of  the  front  surface  of  the  lens  is  10  mm., 
and  of  the  back  surface  is  6  mm.  Calculation  of  the 
optical  efficiency  of  the  eye  from  these  figures  gives  it  a 


DIOPTRICS   OF  THE   EYE  103 

value  of  from  60  to  66  diopters.'  An  eye  with  a  length  of 
axis  of  22  mm.  must  have  a  strength  of  66  diopters  if  the 
rays  are  to  be  f ocussed  upon  the  retina.  It  is  assumed 
that  the  normal  eye  has  a  strength  of  64.50  D.  The  nodal 
point,  the  point  through  which  all  light  rays  may  be 
assumed  to  pass,  is  15.5  mm.  from  the  retina  and  about 
7.3  back  of  the  cornea.  One  can  think  of  the  action  of 
the  lens  most  readily  after  the  analogy  of  a  pin-hole 
camera.     Rays   of   light   pass   through   a   pin   hole  in   a 


Fig.  3g.  —  The  formation  of  the  retinal  image.  Shows  refraction  of  three  rays 
of  light  from  X  and  Y  that  focusses  them  on  the  retina,  and  the  inversion  of  the 
object.    P  is  refracting  surface  of  reduced  eye.     (From  Foster's  "Physiology.") 

screen  in  a  straight  line  from  the  object  to  the  image.  In 
the  lens  the  rays  also  act  as  if  they  passed  through  a  single 
point,  the  nodal  point.  In  the  average  eye,  the  nodal  point 
is  15.5  mm.  in  front  of  the  retina  and  7.3  mm.  back  of  the 
cornea.  The  size  of  the  retinal  image  cast  by  objects  in 
the  outside  world  and  other  relations  of  Hght  rays  are  suffi- 
ciently accurately  determined  for  most  purposes  if  one 
assumes  this  position  for  the  nodal  point,  and  that  the  prin- 
cipal rays  pass  through  it  on  the  way  to  the  retina. 

^  A  diopter  is  defined  as  the  strength  of  a  lens  that  will  bring  parallel 
rays  to  a  focus  at  a  distance  of  one  metre.  The  number  of  diopters  of  a 
lens  is  determined  by  dividing  one  metre  by  the  length  of  its  principal 
focus.  A  lens  that  brings  parallel  rays  to  a  focus  at  20  mm.  has  a  strength 
of  50  diopters. 


I04        FUNDAMENTALS   OF  PSYCHOLOGY 

The  Structure  of  the  Retina.  —  The  retina  is  practically 
a  part  of  the  central  nervous  system.  It  is  a  very  thin  coat 
of  nerve  tissue  from  .3  to  .35  mm.  in  thickness.  If  we  accept 
the  neurone  theory,  the  retina  is  composed  of  three  layers 
of  neurones,  one  with  the  modified  sensory  epitheUum,  the 
rods  and  cones,  which  receive  the  stimulation;  one  inter- 
mediate layer,  the  bipolar  cells;  and  one  whose  cell 
bodies  are  the  large  gangHon  cells  nearest  the  vitreous 
humor. 

The  rods  and  cones,  the  structures  sensitive  to  light,  are 
directly  in  front  of  the  layer  of  pigment  cells  and  the  choroid 
coat  in  the  outermost  part  of  the  retina.  The  cones  are 
relatively  short  and  thick,  from  4-6  ju  (m  =  -ooi  mm.)  in 
diameter  and  30-40  n  long.  The  rods  are  longer  and  more 
slender,  2-4  m  across  and  40-60  m  long.  They  are  crowded 
about  as  closely  together  as  is  possible,  so  that  the  distance 
from  centre  to  centre  of  the  elements  is  not  much  greater 
than  the  diameter  of  the  single  element.  In  both  the  rods 
and  the  cones  can  be  distinguished  an  outer  section  and  an 
inner  section.  Just  at  the  base  of  the  cones  and  a  little 
distance  away  from  the  rods  is  a  swelling  that  corre- 
sponds to  the  cell-body  of  the  neurone.  The  axones  of 
the  rods  and  cones  come  into  contact  with  the  dendrites 
of  the  bipolar  cells,  and  the  axones  of  these  in  turn  with  the 
dendrites  of  the  large  gangKon  cells.  In  the  fovea  it  is  said 
that  a  cone  connects  with  a  single  bipolar  cell  and  that  in 
turn  with  only  one  ganglion  cell.  Thus  the  impulse  from 
each  cone  in  the  fovea  is  kept  separate  all  the  way  to  the 
brain.  In  other  portions  single  bipolar  cells  make  connec- 
tions with  more  than  one  rod  or  cone.  In  addition  to  these 
direct  lines  of  connection  with  the  central  nervous  system, 
there  is  a  layer  of  cells  between  the  rods  and  cones  and  the 
bipolar  cells  which  serves  to  connect  different  rods  and  cones 


THE   STRUCTURE  OF  THE   RETINA       105 

horizontally.    It  is  possible,  even  probable,  that  some  of  the 
spreading  of  impulses  in  contrast  and  irradiation  takes  place 


Fig.  40.  —  Section  o£  the  retina,  showing  the  neurones.     (After  Cajal,  from  How- 
ell's "Physiology.") 

over  these  horizontal  cells.  In  addition  to  these  nerve  cells, 
throughout  the  retina  are  found  supporting  cells  of  non- 
nervous  tissue,  the  so-called  Mtiller  cells.  In  the  innermost 
layer  are  fibres,  the  axones  of  the  ganglion  cells,  which  unite 


io6        FUNDAMENTALS   OF  PSYCHOLOGY 


to  constitute  the  optic  nerve  and  carry  impulses  to  the  cere- 
bral nervous  system. 

Fovea  and  Blind  Spot.  —  Certain  parts  of  the  retina  show 
modifications  from  this  general  arrangement  that  make 
them  of  particular  interest.  One  of  these,  the  fovea,  hes 
near  the  centre  of  the  retina.  It  is  the  point  of  clearest 
vision,  the  point  turned  towards  objects  we  desire  to  see 
distinctly.  As  its  name  implies,  it  is  a  pit  or  depression  in 
the  retina  made  by  a  drawing  apart  of  the  front  coats  of  the 


Fig.  41.  —  Section  of  the  fovea.  It  may  be  seen  that  the  axones  of  the  cones 
extend  toward  the  periphery  to  make  connection  with  bipolar  and  ganglion  cells. 
On  the  left  may  be  seen  the  central  cells  to  which  the  visual  impulse  is  carried. 
F,  fovea;  A,  B,  b,  cones;  a,  rods;  c,  d,  bipolar  cells;  D,  E,  ganghon  cells.  This 
section  is  inverted  as  compared  with  Figs.  39,  40.    (From  Cajai.) 

retina.  This  pit  is  due  to  the  fact  that  axones  which  lead 
off  from  the  cones  go  towards  the  periphery  of  the  fovea, 
and  the  bipolar  and  ganglion  cells  with  their  axones  and  the 
blood  vessels  which  supply  the  region  are  to  one  side  of  the 
cones  rather  than  in  front  of  them,  —  between  them  and 
the  light,  —  as  in  other  portions  of  the  retina.  The  cones  are 
here  nearest  the  surface,  and  light  need  not  pass  through  so 
much  retinal  tissue.  In  the  fovea,  too,  are  found  only  cones, 
and  these  are  as  long  and  slender  as  rods,  so  that  the  centres 
are  only  about  2-4  /i  apart.  In  the  neighborhood  of  the 
fovea  the  retina  has  a  yellowish  tinge.  The  fovea  is  0.3-0.4 
mm.:    the  rod-free  area  about  0.8  mm.  in  diameter.    The 


RODS  AND  CONES  ARE  ORGANS  OF  VISION     107 


yellow  spot  is  larger,  1-3  mm.  in  diameter.  In  psycho- 
logical writings  the  fovea,  point  of  clearest  vision,  and  yel- 
low spot  are  used  almost  interchangeably.  This  is  only 
approximately  accurate,  as  the  dimensions  of  the  yellow 
spot  and  fovea  show.  As  one  proceeds  from  the  fovea,  the 
rods  become  relatively  more  numerous,  the  cones  less  nu- 
merous, until  at  the  periphery  the  cones  are  almost  entirely 
lacking.  Another  region  that  deserves  special  mention  is 
the  bhnd  spot,  the  area  at  which  the  optic  nerve  leaves  the 
eye.  This  contains  no  rods  or  cones,  but  only  the  fibres, 
axones  of  the  large  ganglion  cells,  which  unite  to  form  the 
optic  nerve.  It  is  an  area  about  1.5  mm.  (4°-6°)  in  diameter, 
about  5  mm.  (15°)  to  the  nasal  side  of  the  fovea. 

The  Rods  and  Cones  are  the  Organs  of  Vision.  —  There 
is  very  good  evidence  that  the  rods  and  cones  are  the  organs 
of  vision,  i.  Vision  is  absent  where  the  rods  and  cones  are 
lacking  at  the  en- 
trance of  the  op- 
tic nerve.  2.  The 
shadows  of  the 
blood  vessels  in 
the  outer  coat  of 
the  retina  may  be 
seen  under  suit- 
able conditions, 
and  H.  Miiller 
has  measured  the 
distance  of  these  blood  vessels  from  the  perceiving  organs 
by  a  method  of  triangulation  based  on  the  apparent 
displacement  of  their  shadows  with  known  motion  of  the 
light  outside.  He  found  that  the  blood  vessels  were  from 
0.17-0.33  mm.  from  the  perceiving  coat,  and  measurements 
showed  that  the  actual  distance  in  the  retina  between  blood 


Fig.  42. —  Optogram.  /  shows  the  normal  appear- 
ance of  the  rabbit's  retina;  2  shows  the  condition  when 
the  rabbit  has  been  permitted  to  look  at  the  window  of 
the  dark  room  and  then  is  killed  while  still  in  the  dark 
and  the  retina  fixed  as  a  photographic  negative  is  fixed. 


io8        FUNDAMENTALS   OF  PSYCHOLOGY 


vessels  and  the  layers  of  rods  and  cones  was  from  0.2  and 
0.3  mm. 

The  problem  as  to  what  changes  go  on  in  the  retina  when 
it  is  stimulated,  what  actually  makes  one  see,  has  aroused 
much  discussion.  Two  changes  can  be  seen  to  take  place. 
One  is  a  change  in  the  color  of  the  pigment  in  the  rods.  The 
retina  of  a  frog  killed  in  the  light  has 
a  very  light  color.  If,  however,  it  be 
killed  after  being  kept  a  long  time  in 
the  dark,  the  rods  have  a  dehcate 
purple  hue.  Pictures  may  be  taken 
with  the  retina  of  a  rabbit.  If  the 
rabbit  looks  for  a  Httle  time  at  the 
window  of  a  dark  room  in  which  it  is 
placed,  then  is  killed  and  the  retina 
fixed  as  one  would  fix  a  photographic 
plate,  a  picture  of  the  window  can 
be  seen  on  the  retina.  Such  an  opto- 
gram is  shown  in  Figure  42.  It  has 
also  been  demonstrated  by  a  similar 
method  that  the  cones  contract  in  a 
bright  hght.  Between  the  choroid  and  the  retina  is  a  layer 
of  large  pigment  cells  regarded  by  some  authorities  as  be- 
longing to  the  choroid,  by  others  as  an  independent  inter- 
mediate coat,  and  by  still  others  as  a  part  of  the  retina. 
These  large  hexagonal  cells,  Kke  the  black  paint  on  the 
inside  of  a  camera,  insure  the  absorption  of  errant  hght  rays. 
When  the  eye  has  been  for  a  long  time  in  the  light,  the  cells 
are  well  down  in  the  outer  coat  of  the  retina,  and  adhere  to 
it.  In  the  dark-adapted  eye,  on  the  other  hand,  they  are 
well  outside  and  come  away  from  it  freely  when  the 
choroid  is  stripped  off.  Of  these  changes  only  the  bleaching 
of  the  visual  purple  has  been  given  any  meaning,  and  that, 


Fig.  43.  —  Showing  posi- 
tion of  pigment  cells.  In  the 
dark  -  adapted  eye  (rights 
they  are  outside  of  the  outer 
layer  of  the  rods  and  cones; 
in  bright-adapted  eye  (left) 
they  are  well  down  between 
the  rods  and  cones.  (From 
Siven  and  Wendt.) 


THE   COLOR  PYRAMID  109 

as  we  shall  see,  acts  only  as  a  sensitizer  of  the  retina. 
(The  positions  may  be  compared  in  Figure  43.) 

Sensations  of  Light 

The  Qualities  of  Vision. — All  theories  of  vision  have  been 
based  upon  a  study  of  visual  phenomena  rather  than  on  a 
study  of  the  physiological  processes.     Knowledge  of  physi- 
ological processes  develops  from  a  study  of  the   laws  of 
sight  rather  than  the  other  way  round.     The  sensations 
from  the  eye  may  be  divided  into  four  different  series.    The 
first  is  the  series  of  pure  spectral  colors,  which  range  from 
red  to  violet.    These  are  paralleled  by  the  changes  in  wave 
length,  and  change  in  wave  length  may  be  regarded  as  the 
cause  of  change  in  hue.     The  second  is  the  brightness  or 
achromatic  series.     It  corresponds  to  the  changes  in  the 
intensity  or  amplitude  of  the  vibration,  provided  the  wave 
lengths  are  suitably  mixed.     The  sensation  series  ranges 
from  black  to  white  through  the  grays  which  are  interme- 
diate.   The  third  series  accompanies  change  in  the  intensity 
of  a  single  wave  length  and  ranges  from  the  most  saturated 
or  complete  color  to  black  at  a  slight  intensity  of  stimulus, 
and  again  from  the  most  saturated  color  to  a  whitish  hue, 
at  the  maximum  intensity.    The  fourth  series  corresponds 
to  the  mixture  of  a  single  wave  length  with  grays  of  the 
same  intensity.    The  sensations  that  result  range  from  the 
pure  color  to  a  gray.      The  amount  of  the  admixture  deter- 
mines what  is  called  the  degree  of  saturation  of  the  color. 
The  pure  color  is  saturated,  and  the  greater  the  amount  of 
gray,  the  less  the  saturation.     The  last  two  variations  are 
frequently   mixed;    saturation  and  brightness  frequently 
change  together. 

The  Color  Pyramid.  —  The  four  series  have  been  repre- 
sented schematically  by  a  double  pyramid  (Fig.  44).    The 


no        FUNDAMENTALS   OF  PSYCHOLOGY 


four  primary  colors  red,  yellow,  green  and  blue  are  at  the 
corners  of  the  central  square,  with  the  intermediate  pure 
spectral  colors  between.  The  oranges  on  the  Kne  between 
red  and  yellow,  the  yellow  greens  between  yellow  and  green, 
and  so  on.  At  the  bottom  is 
black,  and  at  the  top  white. 
The  lines  joining  the  square  with 
the  top  and  bottom  represent  the 
tints  and  shades.  When  a  red 
wave  is  increased  in  intensity 
above  the  point  of  saturation, 
pink,  a  tint,  is  seen;  when  di- 
minished, brown,  a  shade,  is  per- 
ceived. The  central  line  that 
connects  black  with  white  repre- 
sents the  series  of  grays.  The 
various  degrees  of  saturation  are 
represented  by  lines  on  the  base 
of  the  pyramid  from  the  outer 
square,  where  lie  the  spectral 
colors,  to  the  centre  that  repre- 
sents the  neutral  gray.  The 
color  tones  are  more  and  more 
mixed  with  the  neutral  tint  from  the  circumference  in- 
ward until  color  altogether  disappears  in  the  centre. 
The  fact  that  the  color  may  be  mixed  with  a  gray  of 
greater  or  less  brightness  and  so  reduced  in  saturation 
and  changed  in  brightness  at  the  same  time,  can  be  repre- 
sented on  the  pyramid  by  lines  from  the  base  of  our  double 
pyramid  to  a  point  on  the  central  line  at  any  distance  above 
or  below  the  base.  That  the  spectral  colors  are  of  different 
brightnesses  has  been  represented  by  tilting  the  square  base 
more  or  less,  making  the  yellow  corner  higher   than  the 


Fig.  44.  —  Color  Pyramid. 
(From  Titchener's  "Textbook  of 
Psychology.") 


COLOR   MIXTURE  iii 

blue.  We  shall  treat  each  of  these  series  of  sensations 
separately  as  far  as  possible. 

Hue.  —  We  may  begin  with  the  colors  of  the  spectrum. 
The  spectrum  is  a  continuous  series  of  colors  which  shade 
one  into  the  other  with  no  breaks  readily  observed  at  the 
first  glance.  The  one  fact  that  has  been  emphasized  by 
direct  observation  is  that  there  are  certain  turning  points 
in  the  apparently  continuous  series,  points  where  one 
quahty  gradually  disappears  and  another  gradually  begins 
to  show  itself.  Thus,  at  the  long-wave  end,  red  predomi- 
nates. As  one  moves  the  eye  toward  the  short-wave  end, 
red  gradually  becomes  less  and  less  pronounced  until  it  is 
finally  lost  at  588  X  in  the  yellow,  which  has  also  been  pres- 
ent in  some  degree  from  the  beginning.  When  red  dis- 
appears, green  begins  to  appear  and  gradually  increases. 
In  the  meantime  yellow  gradually  diminishes  in  amount 
until  it  disappears  at  526  X  and  blue  takes  its  place.  Still 
another  of  these  critical  points  occurs  farther  on  at  484  X, 
where  the  green  disappears  and  is  replaced  by  the  red  of  the 
violet  colors  at  the  short-wave  end. 

Color  Mixture.  —  The  terms  we  have  used  imply  that 
there  are  in  the  spectrum  relatively  few  simple  colors  and 
that  any  two  of  these  may  be  distinguished  in  the  inter- 
mediate colors.  All  theories,  ancient  and  modern,  have 
been  an  attempt  to  discover  just  what  these  simple  colors 
are,  and  to  determine  how  they  combine  to  produce  the 
other  colors.  The  first  experimental  indication  of  the  fact 
that  most  colors  are  compound  is  obtained  from  color  mix- 
ing. Colors  may  be  mixed,  either  by  having  two  different 
wave  lengths  of  hght  fall  upon  the  same  spot  of  the  retina 
at  the  same  time,  or,  more  conveniently,  by  rotating  disks 
of  the  colors  to  be  mixed  so  rapidly  that  one  color  appears 
before   the   effect   of   the   other   has   disappeared.     Both 


112        FUNDAMENTALS   OF  PSYCHOLOGY 

methods  give  approximately  the  same  results.  The  first 
law  of  color  mixture  is  that  two  spectral  colors  when  mixed 
give  a  color  that  Hes  between  them  in  the  spectrum.  When 
the  colors  He  near  together,  the  resulting  color  approaches 
saturation;  the  farther  apart  the  two  colors  in  the  spectrum, 
the  less  is  the  saturation.  Not  only  may  we  obtain  spectral 
colors  from  the  mixture  of  spectral  colors,  but,  if  different 
proportions  of  the  extreme  ends  of  the  spectrum  be  mixed, 
colors  are  produced  that  correspond  to  no  single  wave 
length  but  are  nevertheless  true  color  tones  of  a  high  degree 
of  saturation.  These  are  the  purples,  mauves,  and  other 
similar  quahties.  Since  they  grade  from  red  to  violet,  they 
may  be  regarded  as  filHng  the  gap  between  the  two  ends  of 
the  spectrum.  For  sensation,  then,  the  series  of  colors  can 
best  be  pictured  as  a  closed  figure  rather  than  as  a  straight 
line.  The  direct  psychological  evidence  for  this  is  that  the 
two  ends  of  the  spectrum  are  more  alike  than  are  points 
nearer  together.  Violet  has  a  greater  similarity  to  red  than 
has  any  spectral  color  beyond  pure  yellow,  and  the  two  ends 
of  the  spectrum  may  be  joined  by  suitable  mixtures  of  the 
extreme  colors. 

The  Primary  Colors.  —  All  agree  that  the  colors  we  see 
in  the  spectrum  are  due  to  the  stimulation  of  relatively 
few  processes  in  the  retina.  These  colors  which  may  be 
regarded  as  pure  are  called  primary.  What  the  simple 
processes  are  has  been  in  dispute  between  two  opposing 
groups  of  theories.  One,  represented  by  Young,  Helm- 
holtz,  and  their  followers,  uses  the  facts  of  color  mixing  as 
a  criterion  and  so  chooses  three,  the  smallest  number  of 
colors  that  will  give  all  of  the  other  hues  by  mixing,  and 
of  the  possible  groups  of  threes,  selects  those  that  produce 
all  of  the  others  in  the  maximum  of  saturation.  These  are 
red  of  the  end  of  the  spectrum,  green  of  approximately 


THE   PRIMARY   COLORS  113 

526  X,  and  blue  or  violet  475-430  X.  For  these  three-color 
theories,  yellow  is  a  compound  of  green  and  red.  A  theory 
that  would  make  four  primary  colors  the  basis  for  the 
composition  of  the  spectrum  was  suggested  first  by  Leonardo 
da  Vinci  and  has  received  support  on  the  more  physiological 
side  by  Hering.  Hering's  four  colors  also,  when  combined, 
give  the  spectrum  and  in  even  greater  saturation  than  the 
three  colors.  He  chooses  a  red  which  is  a  combination  of 
a  little  blue  with  the  spectral  red,  a  yellow  of  575  X  while 
the  green  is  of  495  X  and  blue  of  471  X.  The  spectral  values 
for  red  and  green  in  particular  are  relatively  uncertain 
since  they  vary  somewhat  for  different  observers.  But  it 
will  be  noticed  that  the  green  is  of  a  considerably  shorter 
wave  length  for  Hering  than  for  Helmholtz.  Helmholtz' 
green  would  be  a  yellow  green  for  Hering,  while  his  red 
would  be  a  yellowish  red.  Hering  states  that  the  reason 
that  Helmholtz  asserted  that  red  and  green  combine  to  give 
yellow  was  because  Helmholtz  chose  both  red  and  green 
with  a  yellowish  hue,  and  when  mixed  red  and  green  cancel, 
leaving  the  yellov/  predominant. 

That  the  spectral  colors  are  derived  from  a  relatively 
small  number  of  simple  colors  seems  demonstrated,  first, 
by  the  fact  that  colors  similar  to  those  produced  on  the 
retina  by  single  wave  lengths  of  light  can  also  be  excited  by 
stimulating  the  retina  with  two  different  wave  lengths 
suitably  chosen;  and  secondly  by  the  fact  that  the  purples, 
which  physically  are  always  mixed  colors,  seem  just  as  true 
colors  as  those  produced  by  a  single  wave  length.  Irrespec- 
tive of  the  number  and  character  of  the  simple  colors,  it  is 
assumed  by  all  theories  that  there  are  separate  substances 
or  processes  in  the  retina  for  each  of  the  primary  colors, 
and  that  these  simple  structures  or  processes  combine  their 
effects  in  some  way  in  the  production  of  composite  colors. 


114        FUNDAMENTALS   OF  PSYCHOLOGY 

It  is  further  asserted  that  other  than  the  primary  colors 
aroused  by  single  wave  lengths  are  really  mixed  colors, 
physiologically.  Thus  blue-green  in  the  spectrum  produced 
by  a  single  wave  length  is  physiologically  compound,  due 
to  the  simultaneous  action  of  the  blue  and  the  green  organ 
or  process. 

The  Nature  of  White  Light.  —  A  second  law  of  color 
mixing  is  that  certain  spectral  colors  when  mixed  in  the 
right  proportions  produce,  not  an  mtermediate  color,  but 
a  colorless  sensation,  a  gray,  whose  shade  depends  upon 
the  amplitude  of  the  light  waves.  Colors  which  cancel  each 
other  in  this  way  are  called  complementary  colors.  This 
brings  us  to  a  consideration  of  the  physical  nature  of  white 
hght  with  its  darker  tones  of  gray  and  black.  There  are  no 
single  wave  lengths  that  give  rise  to  these  brightnesses. 
They  are  produced  only  when  certain  properly  chosen 
combinations  of  wave  lengths  affect  the  retina.  In  the  sun- 
hght  all  the  colors  of  the  spectrum  are  present,  but  the  result 
for  sensation  is  a  somewhat  yellowish  white,  owing  to  domi- 
nance of  the  yellow  Hghts. 

Complementary  Colors.  —  To  produce  white,  the  simple 
wave  lengths  must  be  present  in  the  right  number  and  pro- 
portion. Both  theories  assume  that  white  or  gray  Kght  is 
produced  when  all  of  their  primary  colors  are  present  in 
the  proper  balance.  For  Helmholtz  all  must  excite  the 
retina  at  the  same  time,  while  Hering  asserts  that  white  is 
seen  whenever  both  components  of  either  of  his  comple- 
mentary pairs  of  simple  colors  are  active  in  the  same  degree 
—  when  red  combines  with  green  or  yellow  with  blue  — 
and  that  they  are  all  present  in  the  spectrum  in  almost  the 
proper  balance  to  neutralize  each  other.  This  explains  the 
fact  mentioned  in  connection  with  the  first  law,  that  spec- 
tral colors  when  mixed  do  not  give  a  saturated  color  and 


SENSATIONS   OF   COLOR 


15 


that  the  farther  apart  they  are  in  the  spectrum  the  less 
saturated  they  become.  Colors  farther  apart  are  more 
nearly  complementary,  and  so  more  white  is  present  in  the 
compound.  The  Hst  of  wave  lengths  of  colors  that  are 
complementary  is  given  in  Table  I.  It  will  be  seen  that 
no  simple  statement  can  be  made  of  the  relation  of  the 
wave  lengths  of  complementary  colors.  Each  must  be 
determined  for  itself.     As  a  result  of  the  facts  stated  in 


Table  I 

—  Table  of  Complementary  Colors  for 

Two  Observers 

Observer  von  Kries 

Observer 

VON  Frey 

Long  Light  Wave 

Complementary- 

Long  Light  Wave 

Complementary 

in  MM 

Short  Wave 

in  MM 

Short  Light  Wave 

656.2 

492.4 

656.2 

485-2 

626 

492.2 

626 

484 

6 

612  ^ 

489.6 

612   3 

483 

6 

599 

5 

487.8 

599 

5 

481 

8 

587 

6 

484.7 

587 

6 

478 

9 

579 

7 

478.7 

586 

7 

478 

7 

577 

6 

473-9 

577 

7 

473 

9 

575 

5 

469 -3 

572 

8 

469 

3 

572 

9 

464.8 

570 

7 

464 

8 

571 

I 

460.4 

569 

0 

460 

4 

570 

4 

440.4 

566 

3 

440 

4 

570 

I 

429-5 

566.4 

429-5 

this  law  it  may  be  asserted  that  each  color  has  a  comple- 
ment, that  all  colors  go  in  pairs,  although  the  colors  in  the 
middle  of  the  spectrum  have  non-spectral  colors  as  their 
complements.  In  terms  of  the  four-color  theory  each  pri- 
mary color  has  a  complement  —  green  is  the  complement 
of  red,  blue  of  yellow.  As  each  combination  of  two  colors 
is  made  up  of  two  simple  colors,  there  is  always  a  second 
combination  of  two  colors,  each  complementary  to  one 
member  of  the  first  pair,  which  when  mixed  give  gray. 

Color  Blindness.  —  The  phenomena  of   color  blindness 
offer  much  aid  to  an  understanding  of  color  vision.    Some 


ii6        FUNDAMENTALS   OF  PSYCHOLOGY 

three  to  five  per  cent  of  men  and  a  much  smaller  percentage 
of  women  are  found  by  tests  to  be  unable  to  distinguish  red 
and  green.  To  them  certain  reds  and  greens  look  exactly 
alike.  When  the  proper  changes  in  brightness  are  made, 
red  and  green  papers  look  gray  and  all  three  may  be  con- 
fused. The  fact  of  confusion  has  been  noted  for  a  long  time. 
The  chemist  Dalton  furnished  one  of  the  first  instances 
recorded,  and  for  a  long  time  the  defect  was  known  as 
Daltonism.  It  is  only  recently  that  fairly  general  agree- 
ment as  to  the  explanation  has  been  reached.  Young  and 
Helmholtz  and  their  followers  were  of  the  opinion  that  one 
might  be  bhnd  to  only  one  color,  one  might  be  red-blind  or 
green-bhnd,  or  both.  Studies  by  Von  Kries  and  others  who 
were  originally  pupils  of  Helmholtz  convinced  them,  how- 
ever, that  on  the  whole  Hering  was  right  in  his  statement 
that  when  one  of  a  pair  of  complementary  colors  could  not 
be  seen,  the  other  was  also  wanting.  In  brief,  the  red-blind 
individual  is  also  green-bhnd  and  sees  both  colors  as  grays. 
Still  rarer  are  the  cases  in  which  the  sufferer  sees  no  colors, 
but  only  grays.  One  other  case  is  rarest  of  all  in  which  the 
patient  is  blue-yellow  bhnd,  and  can  see  red  and  green,  but 
not  blue  or  yellow. 

Peripheral  Vision.  —  Closely  related  to  the  phenomena 
of  color  bhndness  is  the  vision  on  the  peripheral  retina  of  the 
normal  eye.  It  may  be  said  that  every  eye  has  in  it  a  red- 
green  bhnd  area  and  a  totally  color  bhnd  area.  If  one  will 
look  at  any  color  out  of  the  side  of  the  eye,  it  will  be  seen 
that  the  colors  undergo  a  marked  change.  One  can  see  the 
full  range  of  colors  only  for  twenty  or  thirty  degrees  from 
the  fovea;  the  chstance  varies  with  the  individual  and  with 
the  diagonal  that  is  used.  Beyond  that  one  can  see  no  reds 
or  greens,  but  for  ten  degrees  or  so  farther  blues  and  yellows 
alone.  Beyond  that  grays  only  are  perceived.    The  field  of 


SENSATIONS   OF   COLOR  117 

vision  for  colors  and  for  grays  extends  much  farther  on  the 
temporal  side  and  below  than  on  the  nasal  side  and  above. 
Different  experiments  will  not  ordinarily  show  that  members 
of  the  same  pair  of  colors  vanish  sharply  at  the  same  point, 
since  the  point  of  disappearance  depends  upon  the  size  of 
the  colored  surface,  upon  the  saturation  and  tone  of  the 
color,  upon  the  brightness  of  the  color,  and  upon  its  con- 
trast with  the  background,  and  care  must  be  taken  to  obtain 
standard  stimuh  and  conditions.  When  all  the  colors  used 
have  the  same  values  in  these  respects,  the  colors  vanish  by 
pairs  as  indicated  above. 

These  facts  of  color  bhndness  and  of  peripheral  vision 
indicate  that  the  four  primary  colors  are  closely  joined  in 
pairs.  A  study  of  the  colors  that  remain  to  the  color  blind 
and  of  the  way  colors  vanish  on  the  periphery  of  the  eye  is, 
then,  an  important  aid  in  determining  which  are  the 
primary  colors.  That  there  are  four  colors  rather  than  three 
becomes  e\ddent  from  the  fact  that  first  red  and  green  dis- 
appear and  then  yellow  and  blue. 

Negative  After-images.  —  Two  other  subordinate  phe- 
nomena emphasize  the  opposition  between  these  pairs  of 
colors.  These  are  the  negative  after-image  and  contrast. 
One  may  obtain  a  negative  after-image  if  one  looks  for  sev- 
eral seconds  at  any  color  and  then  for  a  couple  of  seconds 
at  a  neutral  surface.  The  negative  after-image  is  a  fainter 
patch  of  the  complementary  color  which  gradually  makes 
its  appearance  upon  the  neutral  surface  and  remains 
for  several  seconds.  The  length  of  time  that  it  lasts 
depends  upon  the  intensity  of  the  original  color,  upon  its 
duration,  and  the  extent  of  the  surface  stimulated, 
and  upon  the  degree  of  fatigue  of  the  eye.  If  two  primary 
colors  are  present  in  the  inducing  stimulus,  the  complement 
of  each  will  be  present  in  the  after-image.     Thus  purple 


ii8        FUNDAMENTALS   OF  PSYCHOLOGY 

gives  a  yellow-green  after-image,  and  orange,  a  greenish- 
blue  after-image.  The  complete  explanation  of  this  phe- 
nomenon can  best  be  discussed  in  connection  with  the  theo- 
ries of  color.  We  may  be  content  here  to  regard  it  as  an- 
other indication  of  the  fact  that  complementary  colors 
stand  in  a  very  close  relation  to  each  other. 

Contrast.  —  The  laws  of  contrast  may  be  stated  in  terms 
very  similar  to  those  used  for  the  after-image,  different  from 
it  only  in  that  one  relation  is  spatial,  the  other  temporal. 
One  has  been  called  successive,  the  other  simultaneous  con- 
trast or  induction.  Wherever  a  color  stimulates  the  retina, 
a  complementary  color  is  induced  in  the  surrounding  area. 
The  brightness  of  the  induced  color  and  the  size  of  the  halo 
depend,  again,  upon  the  brightness  of  the  color,  its  size,  and 
upon  the  similarity  in  brightness  between  the  color  and  its 
background.  Contrast  colors  can  be  seen  most  easily  if  a 
colored  hght  and  a  white  light  are  admitted  to  a  dark  room 
and  a  rod  casts  a  gray  shadow  on  the  colored  surface.  The 
shadow  will  appear  in  the  complement  of  the  color.  Thus 
shadows  on  the  grass  are  purple,  those  on  the  snow  in  yel- 
low sunshine  are  blue,  etc.  A  gray  strip  of  paper  on  a  col- 
ored surface  also  takes  on  a  color  complementary  to  the 
paper,  but  it  is  not  so  easily  seen  by  the  beginner.  If  one 
will  cover  the  entire  surface  with  tissue  paper,  the  contrast 
color  comes  out  clearly.  In  general,  the  rule  holds  that  the 
less  definite  the  contour  between  the  inducing  and  the 
induced  color,  the  more  definite  the  contrast.  The  indi- 
vidual has  become  so  accustomed  to  seeing  contrast  colors 
that  he  forms  the  habit  of  allowing  for  them  and  sees  the 
objects  in  the  colors  that  they  would  have,  were  they  alone. 
He  has  learned  that  a  gray  strip  of  paper  looks  red  on  a  green 
background  and  sees  the  gray  that  is  known  to  be  the  real 
color  of  the  paper  in  spite  of  its  appearance.    The  tissue 


THE  ACHROMATIC   SERIES  119 

paper  makes  it  difficult  to  be  sure  that  the  gray  strip  is 
really  a  separate  object  on  a  colored  surface,  the  habitual 
interpretation  is  not  applied,  and  the  contrast  color  that  is 
really  present  on  the  retina  is  seen. 

Summary  of  Facts  of  the  Chromatic  Series.  —  Of  the 
pure  spectral  colors  we  may  assert  that  all  are  combined 
from  four  primary  colors,  —  red,  green,  yellow,  and  blue 
—  and  that  these  four  colors  are  paired  in  most  of  their 
activities,  red  with  green,  and  yellow  with  blue.  Each 
when  mixed  with  its  complement  gives  gray.  In  color 
bUndness  and  on  the  peripheral  retina,  red  and  green,  yellow 
and  blue,  disappear  together.  When  one  of  these  colors 
stimulates  the  retina,  its  complement  appears  in  the  after- 
image. The  complement  also  irradiates  from  its  surface, 
giving  the  contrast  color. 

The  Achromatic  Series.  —  The  achromatic  series  is  less 
rich  in  sense  quaUties.  It  contains  only  the  series  of  grays, 
ranging  from  black  to  white.  There  are  no  breaks  or  turns 
in  it  as  in  the  color  series.  Like  the  color  series  it  shows 
the  phenomena  of  positive  and  negative  after-images,  of 
contrast,  and  of  mixture,  in  so  far  as  two  grays  when  mixed 
give  an  intermediate  shade.  The  physical  conditions  of 
seeing  the  achromatic  series  are  impHed  in  the  name. 
Whenever  colors  are  ehminated  in  any  way,  the  gray  alone 
is  seen.  There  are  five  conditions  under  which  this  ehmina- 
tion  may  be  brought  about:  by  combining  colors  in  pairs 
of  complements,  discussed  on  page  114;  by  reducing  the 
intensity  of  the  light;  by  reducing  the  size  of  the  area 
affected;  by  reducing  the  time  of  stimulation;  by  stimu- 
lating with  any  wave  lengths  the  periphery  of  the  retina 
or  a  totally  color  bhnd  retina.  These  facts  indicate  that 
there  is  a  different  organ  for  brightness  and  that  this  organ 
is   stimulated  in   isolation   whenever  the    color  processes 


I20        FUNDAMENTALS   OF  PSYCHOLOGY 

cancel;  when  the  light  is  too  faint  to  arouse  the  color  organs, 
but  will  still  stimulate  the  brightness  organ;  when  the 
duration  is  too  short  to  arouse  the  color  processes;  and 
where  the  color  organs  are  absent  as  on  the  periphery  and 
in  the  color  bhnd  eye. 

The  Duplicity  Theory.  —  Within  the  last  generation, 
evidence  has  accumulated  that  there  are  two  organs  of 
brightness  instead  of  one.  One  of  these  is  in  the  cones;  it 
senses  the  brightnesses  of  moderate  intensity.  The  other  is 
in  the  rods,  is  more  sensitive,  and  appreciates  the  bright- 
nesses in  faint  lights.  It  is  possible  to  compare  the  effects 
of  stimulation  of  the  two  organs,  from  the  fact  that  the 
fovea  has  cones  alone,  and  also  because  of  the  greater 
sensitiveness  of  the  rods.  Three  facts  may  be  adduced  as 
evidence  of  the  difference  in  function  of  rods  and  cones. 
First  the  rods  are  more  sensitive  to  faint  Kghts  than  are 
the  cones.  Second,  the  rods  respond  to  all  wave  lengths 
by  brightness  alone,  while  the  cones  respond  to  different 
wave  lengths  with  different  colors.  Third,  the  rods  are 
more  sensitive  to  the  short  wave  lengths,  the  cones  to  the 
long  wave  lengths.  We  shall  consider  each  of  these  phe- 
nomena separately. 

Adaptation  in  Faint  Light  Vision.  —  The  most  striking 
phenomenon  of  adaptation  is  the  great  increase  in  sensitivity 
of  the  retina  after  a  period  in  the  dark.  After  an  hour 
in  the  dark  the  eye  is  about  loo  times  as  sensitive  as  it  is 
in  ordinary  day  Ught  indoors  and  from  100,000  to  150,000 
times  as  sensitive  as  it  would  be  after  a  long  period  in  the 
bright  sunhght.  Adaptation  continues  for  as  much  as 
sixteen  hours,  but  is  most  rapid  in  the  first  few  minutes  and 
is  relatively  sHght  after  the  first  hour.  It  is  probably  due 
in  very  small  part  to  the  expansion  of  the  pupil,  but  for 
the  greater  part  to  the  visual  purple  wliich   regenerates 


DISSAPPEARANCE   OF    COLOR  121 

after  a  time  in  the  dark,  and  by  some  chemical  action 
increases  the  sensitivity  of  the  chemical  substances  in  the 
rods.  The  fovea  in  an  area  of  about  two  degrees  in  diam- 
eter shows  Uttle  adaptation  to  the  dark.  It  undergoes  a 
quick  adaptation  for  two  or  three  minutes  and  then  remains 
constant.  In  the  dark-adapted  eye  the  most  sensitive 
point  on  the  periphery  according  to  Nagel  may  be  1000 
times  as  sensitive  as  the  fovea.  In  day  light  adaptation  the 
fovea  is  20-40  times  as  sensitive  as  the  periphery.  It  is 
for  this  reason  that  one  can  see  a  faint  star  better  if  one 
does  not  look  at  it  directly  but  sees  it  out  of  the  corner  of 
the  eye.  Adaptation  is  almost  entirely  restricted  to  the 
rods. 

Disappearance  of  Color  with  Reduction  of  Illumination. 
—  The  most  noticeable  difference  between  the  spectrum  as 
seen  at  the  intensity  of  ordinary  day  hght  and  in  the  faint 
Hght  of  a  dark  room  is  that  the  colors  are  altogether  lacking 
at  the  low  intensities  and  the  spectrum  appears  as  a  band 
of  gray  Hght.  As  the  intensity  is  diminished,  the  colors 
disappear  in  different  orders.  The  reds  and  violets  vanish 
first  and  the  orange  is  the  last  to  go.  Mixed  colors  change 
their  hue  with  the  reduction  of  the  hght.  Scarlet  becomes 
orange,  orange,  more  yellow,  and  blue-green  shifts  towards 
blue.  With  the  exception  of  extreme  red,  the  colors  are 
seen  as  brightnesses  after  they  disappear  as  color.  Blue 
has  the  longest  of  these  colorless  intervals.  This  so-called 
'photo-chromatic  interval'  is  not  present  at  the  fovea. 
There  the  colors  are  not  seen  as  grays  after  they  cease  to 
stimulate  the  retina  as  colors.  This  leads  us  to  beheve  that 
the  colors  are  seen  by  the  cones  alone;  brightnesses  of  low 
intensities  are  seen  by  the  rods.  Where  the  rods  are 
lacking  there  is  no  gray  that  persists  after  the  colors 
cease  to  be  seen. 


122        FUNDAMENTALS   OF   PSYCHOLOGY 

The  Purkinje  Phenomenon.  —  The  evidence  from  the 
change  in  brightness  of  different  parts  of  the  spectrum  with 
diminution  of  intensity  is  quite  as  marked.  If  a  red  and  a 
blue  seem  of  equal  brightness  in  ordinary  day  Hght,  the  blue 


r 

r 

. 

"■•.^ 

140 

K 

X 

'■ 

^ 

i^n 

\'-- 

120 

\ 

\ 

\ 

■■^^ 

i  1 

■i 

\ 

•■^ 

90 

'  j 

\-. 

An 

1 

I 

V 

70 

:/ 

' 

\, 

' 

if 

* 

\ 

\;. 

so 

SI 

/ 

\ 

40 

■■'/ 

V- 

■ 

\ 

30 

r 

i 

'V 

<)0 

V 

■■■■■, 

'^ 

s 

M 

•>s 

^- 

■••. 

-. 

'■' 

-^ 

-^ 

..    . 

_ 

5    ~ 

3 

2 

13.S 

I 

s 

16S 

S 

1»S 

a 

N>       09       Cn 


Fig.  45.  —  Chart  showing  relative  brightness  of  red  light  in  the  spectrum  of  gas 
light  for  two  protanopes,  S  and  M,  and  for  two  deuteranopes,  5/  and  /V.  (From 
von  Kries.) 

will  be  much  brighter  in  reduced  illumination.  The  short 
wave  lengths  have  a  much  greater  effect  upon  the  rods 
which  are  active  in  the  faint  light.  In  this  they  stand  to 
the  cones  much  as  the  photographic  plate,  which  registers 
the  shorter  waves  but  not  the  red,  to  the  eye  as  a  whole. 
In  day  Ught  the  brightest  point  in  the  spectrum  is  in  the 


COLOR  BLINDNESS  123 

yellow  X  600  ca.,  while  in  faint  Kght  the  brightest  point 
shifts  well  towards  the  green  X  540  ca.  This  shift  is  known 
as  the  Purkinje  phenomenon.  The  Purkinje  phenomenon 
also  appears  in  the  comparison  of  single  colors.  If  a  red 
and  a  blue  are  equally  bright  in  day  light,  the  blue  will  be 
markedly  brighter  in  a  faint  hght.  This  effect  shows  even 
where  the  lights  are  combined  in  a  gray  which  altogether 
disguises  the  color.  If  one  gray  be  mixed  of  long  wave 
lengths,  red  and  green,  and  another  of  blue  and  yellow  and 
these  grays  be  made  of  equal  brightness  in  day  Hght,  the 
gray  compounded  of  long  wave  lengths  will  be  much 
darker  in  faint  hght.  It  should  be  said  that  in  hght  suffi- 
ciently faint  to  give  the  Purkinje  phenomenon,  the  colors 
will  not  be  seen  as  colors,  but  merely  as  brightnesses.  The 
spectrum  in  faint  hght  is  a  band  of  gray  with  a  relatively 
bright  spot  where  the  green  would  be  in  bright  hght.  That 
the  faint  hght  spectrum  is  seen  with  rods  alone  is  evident 
from  the  fact  that  it  cannot  be  seen  with  the  fovea.  These 
three  phenomena  —  different  adaptation  in  periphery  and 
fovea,  the  lack  of  color  in  faint  hght,  and  the  Purkinje 
phenomenon  —  are  all  to  be  explained  on  the  assumption 
that  both  the  rods  and  the  cones  give  gray,  but  are  differ- 
ently sensitive  to  long  and  short  waves.  The  grays  are  of 
approximately  the  same  quahty.  The  only  difference 
noticed  is  that  according  to  von  Kries  the  gray  from  the 
rods  has  a  shghtly  bluish  tone. 

The  Different  Forms  of  Color  Blindness.  —  The  distinc- 
tion drawn  between  day  Hght  and  twihght  vision,  or  cone 
vision  and  rod  vision,  has  proved  very  fruitful  in  the  inter- 
pretation of  certain  facts  of  color  bhndness.  In  the  long 
controversy  between  Hering  and  Helmholtz  a  standing  point 
of  discussion  was  as  to  whether  there  was  ever  bhndness 
to  red  without  also  bhndness  to  green.    Hering  insisted  that 


124        FUNDAMENTALS   OF  PSYCHOLOGY 


blindness  to  one  was  always  accompanied  by  blindness  to 
the  other.  Helmholtz  regarded  red  and  green  as  independ- 
ent colors  and  asserted  that  one  might  be  bhnd  to  either 
alone.  Observations  seemed  ambiguous.  Most  cases  saw 
only  blue  or  yellow,  but  occasionally  careful  examination 
indicated  that  red  would  be  seen  more  clearly  than  the 
green.  When  the  twiHght  or  rod  vision  was  discovered,  it 
was  soon  found  that  in  the  eye  of  the  totally  color  bhnd 


~ 

- 

~~ 

~ 

- 

" 

\ 

•_■ 

/ 

■ 

\ 

-. 

iiti 

- 

fj 

\ 

-1 

/ 

■ 

'• 

- 

\ 

•. 

1 

,' 

\ 

' 

ll 

\ 

ICO 

1; 

V 

''" 

\ 

'- 

lie 

/ 

\ 

lOU 

^ 

S, 

'' 

/ 

1 

\ 

^• 

lo 

. 

■■/ 

^ 

•~ 

•^ 

/ 

" 

— 1 

i:^ 

^ 



V 

L 

^ 

^ 

u 

— 

_ 

u 

u 

_ 

X 

ri 

_ 

J 

u 

_ 

nt 

Li 

— 

^ 

=ri 

rrjrr. 

M 

£9     ^      ?     S     S     ■•     ^-^ 


>  "t 


5     §     I     I 

1 1 !  I 


t  I 


I     f 


Fig.  46.  —  Brightness  of  prismatic  spectrum  of  gas  light  for  total  color  blind 

,  and  for  twilight  vision  of  normal  eye .    Comparison  with  Fig.  45  shows 

that  both  have  the  same  value  as  the  protanope.     (From  von  Kries.) 

only  the  rods  were  active.  The  patient  could  see  much 
better  in  twihght  than  in  ordinary  day  hght,  the  relative 
brightness  of  spectral  waves  was  the  same  as  that  of  the 
normal  individual  in  twihght,  and  it  was  shown  in  a  number 
of  cases  that  he  was  totally  bhnd  in  the  fovea,  where,  as  has 
been  said,  there  are  no  rods.  In  certain  cases  the  bhndness 
in  the  fovea  was  not  noticed,  but  von  Kries  argues  that  this 
was  probably  due  to  the  difficulty  in  making  observations. 
Not  all  would  agree  that  every  case  of  total  color  bhndness  is 
due  to  lack  of  function  of  the  cones,  but  certainly  many  are. 


COLOR   BLINDNESS 


125 


In  the  application  of  this  discovery  to  the  cases  of  partial 
color  blindness,  measurement  of  the  brightness  values  of  a 
number  of  individuals  indicated  that  the  difference  between 
the  two  types,  called  by  Helmholtz  the  red-blind  and  the 
green-blind,  could  be  traced  to  the  dominance  of  twilight 
brightness  values,  or  to  the  dominance  of  day  light  values. 
Both  types  were  defective  in  both  red  and  green,  but  as 
the  red-bhnd  saw  the  spectrum,  the  long  wave  lengths  were 
much  darker  and  so  the  reds  were  not  noticed.  For  the 
other  type,  the  long  wave  lengths  were  brighter  and  they 


-" 

■'" 

/ 

\ 

'^^ 

/ 

\ 

^ 

' 

/ 

; 

\ 

~\ 

/ 

■ 

S 

1 

■ 

\ 

^ 

/ 

/ 

\ 

/ 

"\ 

■ 

^ 

/ 

..^ 

/ 

■^ 

« 

iO 

66 

/ 

e 

13 

6C 

78 

Si 

S? 

s 

'3 

s. 

iS 

jj 

0 

67S 

Fig.  47.  —  Brightness  of  the  gas  light  spectrum  for  the  periphery  of  the  normal  eye 
,  and  for  protanope .     (From  von  Kries.) 

were  more  likely  to  see  the  reds  than  the  greens.  To  avoid 
the  ambiguities  of  the  older  terms  von  Kries  has  suggested 
that  those  individuals  who  see  the  spectrum  in  the  relative 
brightness  values  of  normal  individuals  in  day  light  be 
called  deuteranope,  those  who  see  it  in  twilight  values 
shall  be  called  protanope.  The  brightness  values  are  the 
same  for  the  protanope,  for  the  totally  color  bhnd,  and  for 
the  twihght  vision  of  the  normal  eye.  On  the  other  hand, 
the  brightness  values  of  the  spectrum  are  also  the  same  for 
the  deuteranopes,  the  normal  eye  in  day  light,  and  the  pe- 
riphery of  the  normal  eye,  as  may  be  seen  from  the  accom- 
panying charts  from  von  Kries  (Figs.  46,  47).     All  this 


126        FUNDAMENTALS   OF   PSYCHOLOGY 

argues  for  two  kinds  of  brightness  vision,  one  by  the  cones, 
the  other  by  the  rods.  While  the  actual  sensations  of  gray 
given  by  the  two  are  not  to  be  distinguished,  the  secondary 
characteristics  are  markedly  different. 

Temporal  Phenomena  of  Vision.  —  The  characteristics 
of  a  color  depend  in  many  ways  upon  the  duration  of  the 
color  stimulus.  StimuH  do  not  produce  their  maximum 
effect  at  once,  nor  does  the  color  cease  at  once  with  the 
excitation.  There  is  always  a  rise  to  full  effect  and  a  gradual 
disappearance.  The  course,  as  has  been  shown  by  Miss 
Bills,  is  different  for  each  of  the  colors,  both  for  the  period 
required  to  attain  its  maximum,  and  for  the  period  of 
decline.  The  curve  varies  for  each  color  and  for  the  differ- 
ent intensities  of  the  color.  At  the  lowest  intensity  used, 
the  order  was  yellow,  red,  green,  and  blue;  for  the  medium 
intensity  it  was  yellow,  green,  blue,  red;  and  for  the  highest 
intensity,  yellow,  red,  green  with  blue  undetermined.  ^ 
These  results  were  obtained  in  the  dark.  They  may  be 
different  for  dayhght  conditions.  When  the  sensation 
reaches  its  maximum,  even  when  the  stimulation  persists,  it 
begins  at  once  to  diminish  its  intensity,  at  first  rapidly,  and 
then  very  gradually  until  all  colors  disappear.  This  gradual 
loss  of  color,  called  adaptation,  can  be  easily  demonstrated 
if  one  will  but  gaze  fixedly  at  a  small  'square  of  color.  The 
disappearance  of  the  color  of  the  glass  when  colored  glasses 
are  worn  illustrates  the  same  phenomenon.  Black  and  white 
also  show  the  same  tendency.  The  rate  of  adaptation  varies 
with  the  color,  so  that  one  component  after  another  may 
vanish. 

After  the  stimulus  is  removed,  the  excitation  continues 
for  a  moment  to  be  of  the  same  quality  as  the  original,  and 

1  Bills,  The  Lag  of  Visual  Sensation.  Monograph  Supplement  of  the 
Psychological  Review,  vol.  28. 


TEMPORAL   PHENOMENA  OF  VISION       127 

then  gradually  dies  out.  This  persistence  is  called  the 
positive  after-image.  The  dying  out  corresponds  to  the 
period  of  rise  of  stimulation.  Both  may  be  regarded,  and 
are  regarded  in  all  theories,  as  an  expression  of  the  inertia 
of  the  color  processes.  They  require  time  to  start  and  to 
stop.  For  a  fraction  of  a  second  the  color  or  gray  persists 
in  approximately  full  brightness.  It  is  this  fact  that  makes 
possible  the  mixture  of  colors  on  rotating  disks.  The  excita- 
tion of  one  color  persists  during  the  excitation  of  the  retina 
by  the  other.  For  practical  purposes  the  effect  is  the  same 
as  if  both  lights  were  active  at  the  same  time,  and  the 
brightness  effect  produced  is  the  average  of  all  the  hghts 
that  are  stimulating  the  eye  during  the  period.  If  the 
rotation  is  less  rapid,  one  obtains  a  rapid  fluctuation  in 
brightness,  the  flicker.  This  flicker  disappears  at  a  lower 
rate  of  rotation  when  colors  are  of  the  same  brightness 
than  when  they  are  of  different  brightnesses.  This  fact 
makes  it  possible  to  compare  directly  the  intensity  of  differ- 
ent colored  Kghts,  a  problem  that  produces  difficulties  for 
ordinary  photometric  methods. 

Aside  from  this  positive  after-image,  if  one  gives  but  a 
single  stimulus  of  relatively  short  duration,  it  will  be 
noticed  that  there  are  at  least  two  other  images  succeeding 
the  first.  After  a  momentary  dark  period  there  comes  a 
complementary  after-image,  usually  with  an  added  slightly 
bluish  hue.  After  another  dark  interval,  an  image  of  the 
same  color  as  the  first  and  usually  fainter  appears,  to  be 
followed  by  another  dark  period.  Including  the  dark 
periods  which  look  like  black  it  is  possible  under  favorable 
conditions  to  see  six  different  images  following  a  colored 
sector  on  a  slowly  rotating  disk.  These  images  are  an  ex- 
pression of  the  fact  that  the  retina  responds  rhythmically, 
that  when  a  retinal  excitation  is  started  it  rises  and  falls  in 


128        FUNDAMENTALS   OF  PSYCHOLOGY 

its  response  in  a  regular  order.  The  second  of  the  images 
mentioned  above  is  assumed  to  be  due  to  the  delayed  exci- 
tation of  the  rods,  the  third  to  a  renewal  of  the  excitation 
of  the  brightness  organ  of  the  cones. 

Interesting  also  is  the  fact  that  it  is  possible  to  excite 
colors  as  an  after-effect  of  brightness.  If  one  will  look  for 
half  a  second  or  so  at  the  setting  sun  and  then  for  a  time 


Fig.  48.  —  Benham  disk. 

watch  the  after-image  as  projected  against  a  neutral  surface, 
one  will  observe  a  slow  succession  of  colors  and  grays  that 
will  last  for  several  minutes.  Helmholtz  gave  the  order, 
with  the  eyes  open,  as  white,  red,  green,  red,  blue.  One 
notes  in  this,  too,  that  the  color  of  an  image  depends  upon 
the  character  of  the  background.  It  will  have  a  different 
color  with  the  eyes  open  and  with  the  eyes  closed.  When  the 
eyes  were  closed,  Helmholtz  found  the  order  to  be  blue, 
green,  yellow.  It  will  also  be  noticed  when  a  black  and  white 
disk  is  revolving  slowly  that  a  series  of  faint  colors  seems 


SPATIAL   PHENOMENA  OF  VISION  129 

to  follow  the  edge  of  the  black  sector.  Similar,  too,  in 
explanation  is  the  color  produced  when  a  white  disk  with 
concentric  rings  of  black  is  rotated.  If  a  disk  similar  to 
that  in  Figure  48  is  rotated  slowly,  the  inner  ring  appears 
purpHsh,  the  outer  greenish.  The  explanation  of  all  these 
phenomena  is  somewhat  uncertain,  but  seems  to  fit  best 
with  the  assumption  of  Helmholtz  that  in  some  way  the 
color  processes  are  excited  by  the  black  and  white  and  that 
the  different  colors  die  out  at  different  rates  and  so  one 
color  will  predominate  at  one  time,  another  at  another. 

The  Spatial  Phenomena  of  Vision.  —  It  has  been  shown 
that  the  visual  excitation  is  not  Hmited  to  the  actual  dura- 
tion of  the  stimulus;  its  influence  is  similarly  not  limited 
to  the  area  stimulated,  but  extends  about  it  in  all  directions 
to  varying  extents.  A  series  of  facts  can  be  adduced  to 
demonstrate  this. 

1.  Bright  colors  always  look  larger  than  dark  ones.  A 
white  square  on  a  black  ground  always  looks  larger  than  a 
black  square  on  a  white  ground.  In  each  case  the  white 
stimulus  spreads  at  the  expense  of  the  black.  Still  more 
striking  is  the  apparent  increase  in  the  size  of  the  filament 
of  the  electric  light  when  it  glows  as  compared  with  its  size 
when  cold. 

2.  A  number  of  small  surfaces  of  two  or  more  colors 
when  in  juxtaposition  fuse  into  a  color  identical  with  that 
given  by  the  same  colors  when  mixed  by  rotation.  Each 
color  extends  beyond  the  area  stimulated,  and  these  exten- 
sions overlap  to  produce  a  continuous  color  of  the  average 
hue  and  brightness  of  all.  The  overlapping  in  space  is 
similar  to  the  overlapping  in  time  in  mixtures  produced  by 
rotating  disks.  In  many  fabrics  it  will  be  noticed  that  the 
dominant  color  seen  at  a  distance  is  a  mixture  of  a  number 
of  threads  of  different  colors. 


I30        FUNDAMENTALS  OF  PSYCHOLOGY 

3.  A  colored  surface  may  be  too  small  to  be  seen  as 
colored  and  may  yet  be  seen  as  gray.  Colored  objects  at  a 
distance  lose  their  color  while  still  visible.  The  size  at  which 
the  color  disappears  varies  for  different  colors.  The  table 
below  gives  the  diameter  of  five  colors  at  which  the  surface 
will  be  seen  as  gray  in  the  first  column  and  at  which  it  will 
be  seen  in  color  in  the  second.  The  column  headed  "  Ratio  " 
gives  the  proportion  between  the  areas  that  can  be  seen  at 
all  and  the  areas  that  can  be  seen  as  colored.  It  will  be 
noticed  that  a  red  surface,  which  is  large  enough  to  be  seen 
at  all,  is  seen  as  red,  while  a  much  larger  area  of  blue  is  seen 
only  as  gray.  Several  bits  of  color,  each  too  small  to  be 
seen  alone,  will  when  close  together  induce  a  color  sensation. 
The  explanation  is  the  same  as  for  the  second  law  above. 


COLORl 

Absolute  Limen 

Color  Limen 

Ratio 

Extreme  red 

0.5 

1 .0 

4 

Orange 

0.9 

2 . 1 

5-5 

Yellow 

I 

3-1 

9.6 

Green 

0.3 

4.2 

196 

Blue 

0.3 

75 

625 

4.  In  some  degree,  size,  duration,  and  intensity  are 
interchangeable.  More  intense  lights  seem  larger,  seem  to 
last  longer,  and,  vice  versa,  within  limits  larger  surfaces  and 
longer  exposures  seem  to  give  more  intense  stimulations. 
Up  to  two  minutes  in  size  doubling  the  intensity  doubles  the 
apparent  size. 

These  various  phenomena  are  to  be  explained  by  the 
spread  of  the  effects  of  the  excitation  in  the  retina,  either 
by  a  spread  of  the  chemical  efifects  from  one  unit  to  another, 
or  by  a  spread  of  nervous  impulses  from  the  cones  or  rod 
stimulated  to  neighboring  ones  through  the  connecting 
neurones  just  inside  the  layer  of  rods  and  cones.  (See 
p.  104.)     Contrast  is  due  to  a  similar  phenomenon,  but  has 

1  From  Charpentier,  Annales  d'ocul.  Ixxix,  1878. 


THEORIES   OF   COLOR  131 

been  described  above,  and  the  explanation  may  best  be  left 
to  the  discussion  of  the  various  theories,  as  the  induction 
of  a  complementary  color  introduces  a  new  principle. 

The  Helmholtz  Theory.  —  A  brief  statement  of  the  more 
important  theoretical  explanations  of  color  may  serve  as  a 
review  of  the  facts.  The  first  of  the  modern  theories  was 
formulated  by  Thomas  Young,  an  Enghsh  physicist,  and 
expanded  by  Helmholtz.  It  assumes  that  there  are  three 
separate  kinds  of  organs  in  the  retina,  that  one  of  these  is 
afTected  most  strongly  by  red,  another  by  green,  and  a  third 
by  blue  or  indigo.  When  all  three  are  excited  at  once,  white 
is  produced.  Red  and  green  when  stimulated  together  give 
rise  to  yellow.  All  the  other  colors  are  produced  by  the 
mixture  of  the  effects  of  two  or  all  three  of  the  organs.  After- 
images are  due  to  the  fatigue  of  some  of  the  organs  and  the 
response  of  those  remaining  when  white  light  falls  upon  the 
retina.  Contrast  is  an  illusion  of  judgment.  The  facts  are 
out  of  harmony  with  the  theory  on  all  but  one  point. 
I .  Yellow  cannot  be  a  compound  color,  since  yellow  may  be 
seen  where  both  its  assumed  components  are  lacking,  on 
the  periphery  of  the  retina  and  by  the  color  blind.  2.  The 
same  objections  hold  against  regarding  white  as  a  com- 
pound. It,  too,  can  be  seen  where  no  one  of  its  components  is 
present.  3.  The  explanation  of  after-images  falls  with  the 
abandonment  of  the  theory  that  white  is  a  compound  color. 
4.  Contrast  is  not  an  illusion  of  judgment,  as  it  is  most 
easily  noticed  where  one  is  not  aware  that  the  inducing 
color  is  present.  The  one  remnant  of  the  Helmholtz  theory 
is  its  explanation  of  color  mixing,  and  the  colors  that  it 
chooses  as  primary  do  not  meet  any  of  the  physiological 
tests.  The  modern  adherents  of  the  Helmholtz  theory  hold 
also  that  it  explains  color  blindness,  although  they  admit 
that  the  partially  color  blind  see  only  blue  and  yellow. 


132        FUNDAMENTALS   OF  PSYCHOLOGY 

They  add  to  the  color  processes  the  rods  as  an  organ  for 
brightness,  but  still  assume  that  the  grays  in  day  light  as 
seen  by  the  cones  are  a  compound  of  all  three  colors. 

The  Hering  Theory.  —  The  Hering  theory  asserts  that 
there  are  two  pairs  of  primary  colors  with  the  elements 
in  each  pair  opposed,  and  an  independent  brightness  organ. 
The  theory  assumes  that  each  pair  of  colors  is  produced  by 
antagonistic  changes  in  the  same  organ.  One  organ  gives 
rise  to  red  and  green,  a  second  to  blue  and  to  yellow,  and  a 
third  to  the  brightnesses,  black  and  white.  The  antagonistic 
processes  are  said  to  be  anabolism  and  catabolism,  the  up- 
building of  the  organ  and  its  deterioration.  Green,  blue, 
and  black  induce  anabolism,  the  others  cataboHsm.  Com- 
plementariness  is  explained  by  the  fact  that  members  ol 
the  same  pair  of  colors  tend  to  induce  opposed  processes  in 
the  same  degree  and  so  produce  no  effect.  When  the  ten- 
dency of  green  to  produce  anaboHsm  and  of  red  to  cause 
catabolism  are  equally  strong,  no  change  in  the  organ  re- 
sults. Since  all  wave  lengths  stimulate  the  brightness 
organ,  gray  is  seen,  and  seen  alone,  when  the  colors  cancel 
each  other.  Color  blindness  is  due  to  an  absence  of  one  or 
more  of  the  organs.  The  red-green  organ  is  most  frequently 
lacking.  Red-green  bhndness  is  most  frequent,  and  red 
and  green  are  least  widely  distributed  on  the  retina.  In 
total  color  bhndness  the  yellow-blue  organ  Is  lacking  also, 
the  white-black  organ  alone  is  present.  Positive  after- 
images are  explained  as  due  to  a  continued  action  of  the 
organ  after  the  stimulus  has  ceased.  In  the  negative  after- 
image anaboHsm  is  followed  by  cataboHsm,  since  the  excess 
material  accumulated  by  the  retinal  excitation  tends  to 
disappear  as  the  Hght  ceases  to  act  and  the  tissues  return 
to  their  normal  balance.  Similarly,  cataboHsm  is  followed 
by  anaboHsm  when  the  stimulation  ceases.     Contrast  is 


THEORIES   OF   COLOR  133 

due  to  one  process  inducing  its  opposite  in  contiguous  areas. 
Excessive  anabolism  in  a  stimulated  area  is  at  the  expense 
of  the  nourishment  of  the  other  adjoining  areas,  and  cata- 
bohsm  results  there. 

Criticism  of  the  Hering  Theory.  —  The  most  important 
objection  to  the  Hering  theory  is  its  assumption  that  the 
opposed  processes  are  anabolism  and  catabolism.  Nowhere 
in  the  bodily  structures  is  anabohsm  induced  by  stimula- 
tion. If  the  exact  change  be  left  indefinite,  be  regarded  as 
a  rever^ble  chemical  process,  as  Miiller  and  von  Kries  have 
suggested,  nothing  would  be  lost  in  adequacy  of  explanation 
of  the  phenomena  and  much  is  gained  in  credibility.  A 
second  minor  objection,  made  by  Muller,  is  that  it  is  incon- 
sistent to  assume  that  the  opposed  processes  cancel  each 
other  in  the  color  organs,  while  in  the  black-white  organ 
they  give  a  sensation,  the  neutral  gray  of  the  rested  eye. 
Muller  suggests  that  the  white-black  processes  cancel  each 
other,  so  that  when  there  has  been  no  excitation  for  a  long 
time  the  retina  gives  no  sensation,  but  that  the  cortical 
cells,  the  central  organ  for  vision,  produce  the  gray.  As 
evidence  for  this  he  cites  the  fact  that  the  bhnd,  if  not 
blind  from  birth,  always  see  this  gray,  and  that  a  spot  of 
gray  is  seen  where  even  a  small  area  of  the  retina  has  been 
destroyed. 

The  Ladd-Franklin  Theory.  —  A  recent  theory  of  Mrs. 
Ladd-Frankhn  gives  an  evolutionary  theory  of  color  vision. 
She  assumes  that  primitive  vision  in  animals  is  rod  vision 
which  gives  differences  of  brightness  only.  Later  cones 
develop  and  with  them  comes  the  appreciation  of  colors. 
Within  the  cones  there  is  also  a  development.  First  appear 
substances  sensitive  to  blue  and  yellow  alone,  then  the  sub- 
stance sensitive  to  yellow  divides  into  two,  one  sensitive  to 
red  and  the  other  to  green.    Each  more  evolved  organ  may 


134        FUNDAMENTALS   OF  PSYCHOLOGY 

act  as  a  whole  to  give  its  original  sensation.  The  cone 
when  stimulated  as  a  whole  gives  brightness,  the  red  and 
green  acting  together  give  yellow.  The  color-blind  eye  is 
an  undeveloped  eye.  In  red-green  bUndness  the  yellow 
substance  has  not  yet  subdivided,  in  total  color  bhndness 
the  cones  act  only  as  rods.  While  very  ingenious,  its  choice 
of  primary  colors  is  open  to  certain  of  the  objections  to  the 
Helmholtz  theory,  and  it  fails  to  recognize  the  differences 
between  rod  vision  and  cone  vision  as  seen  in  the  Purkinje 
phenomenon  or  to  explain  them  in  an  adequate  manner. 

We  may  emphasize  certain  essential  facts  which  all 
accept.  I.  There  are  four  primary  colors,  distinguished 
from  the  others  by  the  fact  that  they  vanish  without  change 
of  quahty  as  they  are  moved  outward  to  the  periphery.  2. 
These  four  colors  are  arranged  in  pairs,  red  with  green, 
blue  with  yellow.  The  pairs  cancel  when  mixed  in  suitable 
proportions;  one  induces  the  other  as  an  after-image  and 
excites  the  other  on  the  surrounding  areas  of  the  retina.  3. 
There  is  an  independent  brightness  which  is  present  in  all 
colors  and  is  seen  alone  when  the  colors  cancel  each  other, 
at  low  intensities  of  light,  and  where  the  color  organs  are 
lacking.  Physiologically  we  may  assume  an  organ  for  each 
pair  of  colors.  For  this  the  Hering  theory  as  modified  by 
von  Kries  is  as  acceptable  as  any.  That, means  a  single 
organ  for  each  pair  and  in  each  organ  opposed  chemical 
processes.  The  exact  nature  of  the  processes  must  be  left 
undecided.  To  this  must  be  added  the  acceptance  of  a  dis- 
tinction between  rods  and  cones  as  organs  for  brightness. 
They  give  the  same  sensations  of  brightness,  but  the  rods 
are  more  sensitive  absolutely  and  are  also  relatively  more 
sensitive  to  the  short  wave  lengths;  the  cones  more  sensi- 
tive to  the  long. 


THEORIES   OF   COLOR  135 

REFERENCES 

Parsons:  Color  Vision. 

Greenwood:  Physiology  of  the  Special  Senses,  pp.  86-214. 

Helmholtz:  Handbuch  der  physiologische  Optik,  3d  Edition, 
Vol.  II. 

VON  Kries:  Die  Gesichtsempfindung.  Nagel's  Handbuch  d. 
Physiologic,  Vol.  Ill,  pp.  109-279. 

Myers:  Experimental  Psychology,  Chs.  VI,  VII. 

Howell:  Physiology,  Chs.  XVII,  XVIII. 

Titchener:  Experimental  Psj^chology,  Vol.  I,  Pt.  II,  pp.  1-50. 

Mrs.  Ladd-Franklin  :  Article  on  Color,  Dictionary  of  Phi- 
losophy and  Psychology. 


CHAPTER  V 
SENSATION  (Continued) 

Audition 

The  auditory  sensations  stand  next  to  the  visual,  both 
in  complexity  and  in  importance  for  behavior  and  mental 
life  in  general.  We  can  approach  the  study  of  audition  in 
three  different  ways.  Physically,  sound  is  vibration  in  the 
air;  physiologically,  it  is  oscillation  of  some  deHcate  mem- 
brane in  the  ear;  psychologically,  it  is  the  series  of  sensa- 
tions, the  material  of  music  and  human  speech  on  the  one 
hand,  and  the  series  of  noises  and  unorganized  sounds  on 
the  other.  The  physical  processes  consist  of  longitudinal 
oscillations  that  proceed  outward  concentrically  from  the 
vibrating  body.  These  oscillations  vary  in  rate,  which  cor- 
responds to  the  pitch  of  the  tone;  in  amplitude,  which  cor- 
responds to  the  intensity  of  the  tone;  and  in  complexity, 
which  corresponds  to  the  timbre,  or  tone-color. 

The  Structure  of  the  Ear 

The  Divisions  of  the  Ear.  —  The  organ  that  translates 
these  vibrations  in  the  air  into  nerve  processes  is  the  ear. 
The  ear  is  composed  of  three  parts:  the  external  ear,  con- 
sisting of  the  pinna,  commonly  called  the  ear,  and  the 
external  auditory  meatus  or  tube  that  runs  into  the  head; 
the  middle  ear,  an  enlarged  cavity  in  the  skull  separated 
from  the  external  by  the  membrane  of  the  tympanum  or 
drum;  and  the  internal  ear,  a  labyrinthine  cavity  between 
the  middle  ear  and  the  brain  where  the  vibrations  are  trans- 
136 


THE   STRUCTURE   OF   THE   EAR 


1,^7 


lated  into  nervous  impulses.  The  external  ear  needs  no 
description.  The  outer  ear  probably  has  some  influence  in 
collecting  the  vibrations  in  the  air  and  turning  them  into 
the  external  meatus.  The  meatus  itself  is  curved  sUghtly 
and  thus  reduces  to  a  minimum  the  probabiHty  of  injury 
to  the  membrane  of  the  tympanum. 

The  important  structures  of  the  middle  ear  are  the  mem- 
brane of  the  drum,  three  small  bones  that  stretch  across 


Fig.  4g.  ^  Schematic  section  of  the  ear;  M  and  G,  external  ear;  P,  middle  ear 
with  small  bones;  S,  cochlea;  B,  semicircular  canal;  A,  auditory  nerve;  R,  Eu- 
stachian tube.  To  give  a  sectional  view  the  cochlea  is  displaced  90°.  Its  apex 
should  be  turned  toward  the  observer.     (From  Calkins,  after  Martin-Czermak.) 

the  cavity  of  the  middle  ear,  and  the  membrane  which  with 
the  plate  of  the  stirrup  closes  the  oval  window  of  the  inner 
ear.  The  chain  of  bones  consists  of  the  malleus,  incus,  and 
stapes,  named  from  their  shapes,  which  resemble  a  hammer, 
anvil,  and  stirrup,  respectively.  The  handle  of  the  hammer 
is  fastened  to  the  inner  surface  of  the  membrane  of  the 
tympanum,  the  head  is  jointed  into  the  top  surface  of  the 


138        FUNDAMENTALS   OF  PSYCHOLOGY 

anvil,  not  unlike  a  large  molar  tooth  in  shape,  and  is  hung 
by  a  ligament  from  the  top  of  the  cavity  of  the  middle  ear. 
The  stirrup  is  attached  by  a  deHcate  cartilage  to  a  process 
of  the  anvil,  not  unlike  one  of  the  roots  of  the  tooth.    The 


Fig.  so.  —  Tympanum  and  small  bones  seen  from  within  the  middle  ear.  i ,  an- 
vil; 2,  suspensory  ligament  of  hammer;  4,  head  of  hammer;  7,  tendon  of  tensor 
tympani;  8,  foot-piece  of  stirrup  that  fits  into  the  oval  vjrindow;  lo,  handle  of 
hammer  or  manubrium;  11,  tensor  tympani;  12,  membrane  of  the  drum;  13,  Eu- 
stachian tube. 


membranes  and  the  bones  swing  together  on  the  ligament 
as  a  fulcrum.  When  the  air  vibrations  impinge  on  the  mem- 
brane of  the  drum,  it  swings  inward,  carrying  the  hammer 
and  the  other  bones  with  it,  and  the  foot  of  the  stirrup 
pushes  against  the  lymph  of  the  inner  ear,  and  sets  that  in 
vibration  also.  Two  muscles  prevent  movements  strong 
enough  to  rupture  either  membrane.    One,  the  tensor  tym- 


THE  STRUCTURE  OF  THE  EAR 


1,39 


Mcp 


Mm 


Fig.  si. 
middle  ear. 
S,  stirrup. 


—  The    bones    of    the 
M,  hammer;  ./,  anvil; 


pani,  extends  laterally  from  a  bony  canal  inside  of  the  tym- 
panum and  is  inserted  in  the  head  of  the  hammer;  the  other 

the  stapedius,  extends  from  a 

tube  in  the  lower  inner  wall  of 

the  cavity  and  is  inserted  by  a 

long  ligament  in  the  head  of 

the    stirrup    near    where    the 

anvil  is  joined  to  it.    The  two 

muscles    oppose    each    other. 

The    tensor  tympani  tends  to 

draw  the  drum  head  inward, 

the    stapedius    to    draw     the 

stirrup    foot    away    from    the 

oval  window  toward  the  drum 

head.     When    both    contract, 

the  entire  vibrating  mechanism  is  held  firm  and  prevented 

from  making  too  violent  oscillations. 

The  membrane  of  the 
drum,  by  virtue  of  its  coni- 
cal shape,  the  arrangement 
of  the  fibres  that  compose 
it,  and  the  weighting  on 
one  side  only,  has  no  tone 
of  its  own,  responds  to  all 
vibration  rates  impartially, 
and  so  transmits  all  tones, 
whatever  their  pitch,  with 
approximately  equal 
strength.  In  traversing 
Fig.  52. —  Illustrates  the  way  in  which     the  middle  ear,  the  ampH- 

the  three  bones  act  together  as  a  bent        .      1  r    .1  •       j 

lever,      i,    the    handle   of    the    hammer;        tude    of    the    WaVCS    IS    de- 

2,  the  long  process  of  the  anvil;  3,  the     creased  and  their  intensity 

stirrup;  a-b,  the  axis  of  rotation.     (From        .  1  •  1 

Howell's  "Textbook  of  Physiology.")  increased.     This   change 


I40 


FUNDAMENTALS   OF   PSYCHOLOGY 


takes  place  in  two  ways.  First  the  area  of  the  oval  window 
is  much  smaller  than  the  area  of  the  drum,  so  that  the 
energy  is  more  concentrated.  Second,  as  can  be  seen  in 
Figure  53,  the  lever  arm  formed  by  the  handle  of  the  ham- 
mer has  a  greater  effective  length  than  that  formed  by  the 
process  of  the  anvil  to  which 
the  stirrup  is  attached.  Sound 
waves,  then,  traverse  the  oscil- 
lating mechanism  of  the  middle 
ear  with  rate  or  pitch  un- 
changed but  with  intensity  in- 
creased twenty  to  thirty  times 
and  with  a  corresponding  di- 
minution in  ampHtude.  An 
essential  mechanism  for  mak- 
ing possible  the  vibration  of  the 
drum  and  for  protecting  it 
against  rupture  due  to  differ- 
ence between  the  air  pressure 
in  the  outer  air  and  that  within 
the  middle  ear  is  the  opening 
into  the  throat  provided  by 
the  Eustachian  tube.  This  serves  to  keep  the  pressure  of 
the  air  in  the  middle  ear  approximately  equal  to  that  in 
the  outside  world.  The  act  of  swallowing  opens  the  tube 
and  permits  the  interchange  of  air. 

The  Cochlea.  —  The  inner  ear,  or  labyrinth,  is  filled  with 
lymph.  It  has  two  openings  into  the  middle  ear,  both  closed 
by  dehcate  membranes.  One  we  have  mentioned  as  receiv- 
ing the  foot  of  the  stirrup.  The  joint  is  made  watertight  by 
a  membrane.  This  is  the  oval  window.  The  other,  a  little 
below  the  oval  window,  is  closed  by  a  single  membrane. 
From  its  shape  it  is  called  the  round  window.    We  may  dis- 


FiG.  53.  — To  illustrate  the  lever 
action  of  the  ear  bones,  m,  the 
hammer;  e,  the  anvil;  a,  the  short 
process  of  the  anvil  which  abuts 
upon  the  wall  of  the  middle  ear  and 
serves  as  point  of  rotation;  a-b,  the 
power  arm;  a-p,  the  load  arm  of 
the  lever. 


THE   STRUCTURE  OF  THE    EAR 


141 


tinguish  two  parts  of  the  inner  ear,  the  cochlea  and  the 
labyrinth  proper,  —  the  semicircular  canals,  utriculus,  and 
sacculus.    As  the  cochlea  alone  is  concerned  in  hearing,  a 


msp^ 


Fig.  54.  —  Longitudinal  section  of  the  cochlea  of  a  cat;  dc,  cochlear  duct;  gsp, 
spiral  ganglion;  msp,  membrana  spiralis  (basilar  niembrane);  mv,  Reissner's  mem- 
brane; n,  cochlear  nerve;  set,  scala  tympani;  scv,  scala  vestibuli.  (From  Huber, 
after  Sobotta.) 

description  of  the  other  structures  may  be  postponed.  In 
essentials  the  cochlea  is  a  tube  divided  up  its  middle  by  a 
partition  of  bone  and  membrane.  One  side  of  the  partition 
is  closed  by  the  oval  window,  the  other,  or  lower,  by  the 
round  window.    The  tube  is  wound  two  and  a  half  times 


142        FUNDAMENTALS   OF  PSYCHOLOGY 

about  a  central  column  of  bone,  the  modiolus.  The  cochlear 
nerve,  the  nerve  of  hearing,  enters  the  centre  of  the  modiolus, 
and  ascends  to  the  top,  giving  off  a  spiral  band  of  nerves 
from  the  bottom  to  the  top  of  the  cochlea.  It  enters  through 
the  spiral  ridge  of  bone,  the  lamina  spiraHs,  and  ends  in  close 
connection  with  cells  tipped  with  hairs  on  and  about  the 
basilar  membrane.  This  basilar  membrane,  together  with 
the  lamina  spiralis,  constitutes  the  dividing  partition  of  the 
cochlear  tube.  If  one  looks  at  a  section  of  the  cochlea,  one 
sees  five  or  six  sections  of  the  tube  (Fig.  54).  In  each  of 
these  there  are  three  divisions.  The  upper  one  in  the  figure 
is  called  the  scala  vestibuli,  the  staircase  of  the  vestibule, 
since  it  connects  directly  with  the  vestibule  and  the  oval 
window.  A  small  triangular  canal  is  divided  off  by  the  basi- 
lar membrane  and  a  deKcate  membrane  above  it,  Reissner's 
membrane.  This  is  the  cochlear  canal.  Below  the  basilar 
membrane  is  the  scala  tympani,  which  connects  with  the 
round  window.  The  vibrations  of  the  stirrup  are  trans- 
mitted to  the  lymph  through  the  oval  window,  and  ascend 
to  the  top  of  the  cochlea  by  the  scala  vestibuli.  At  the  apex 
is  an  opening  between  the  scala  vestibuli  and  the  scala 
tympani,  which  is  supposed  to  permit  the  vibrations  to 
pass  from  one  to  the  other.  The  delicate  membrane  of  the 
round  window  permits  the  Hquid  to  vibrate  as  it  could  not 
were  there  but  one  opening  to  the  cavity* filled  with  hquid. 
By  virtue  of  these  connections,  the  hquid  in  the  cochlea 
vibrates  at  the  rate  of  the  sound  wave  in  the  air. 

Sensations  oj  Tone 

The  Qualities  of  Tone.  —  The  problem  for  the  theory 
of  hearing  is  how  the  vibrations  in  this  liquid  in  the  cochlea 
may  excite  the  auditory  nerve.  To  answer  this  question 
we  must  turn  to  a  consideration  of  the  facts  of  auditory 


SENSATIONS   OF  TONE  143 

sensation.  The  qualities  of  tone  run  in  a  single  line  from 
low  to  high.  Slow  vibrations  give  low  tones,  rapid  vibra- 
tions high  tones.  The  lowest  tones  that  can  be  heard  vary 
from  about  twelve  to  sixteen  per  second.  The  upper  hmit 
,  was  given  by  Galton  at  50,000,  by  Preyer  at  40,000,  Bruner 
from  22,000  to  43,000  for  different  individuals,  while  Edel- 
mann  asserts  that  some  individuals  can  hear  50,000  vibra- 
tions. Later  investigators,  working  with  more  accurately 
tuned  instruments,  which  however  probably  give  less  in- 
tense tones,  obtain  values  about  20,000  vibrations  per 
second.  The  lower  tones  are  determined  by  means  of  large 
forks,  the  upper  usually  by  a  whistle  with  very  short  barrel, 
first  de\ised  by  Galton,  of  which  a  new  and  more  accurate 
model  has  recently  been  made  by  Edelmann.  The  inter- 
mediate tones  increase  regularly  in  pitch. 

The  accuracy  with  which  the  pitch  of  tones  may  be  dis- 
tinguished varies  markedly  with  the  absolute  pitch.  Tones 
in  the  middle  range  can  be  discriminated  much  more  easily 
than  very  high  tones  or  very  low  tones.  From  64  to  1024 
V  D,^  one  can  distinguish  differences  as  small  as  0.3-0.2  of 
a  vibration.  Above  or  below  this,  tones  must  be  much  more 
different  to  be  distinguished.  At  32  and  2048  V  D  the  addi- 
tion of  0.4  of  a  vibration  can  just  be  noticed,  and  for  very 
high  and  very  low  tones,  many  vibrations  may  be  added 
before  a  difference  is  noted.  One  can  distinguish  tones 
differing  by  these  amounts  and  even  say  which  is  higher 
and  which  lower.  On  the  basis  of  these  experiments  by 
Preyer,  Luft^  and  Max  Meyer^  it  has  been  estimated 
that  one  can  distinguish  approximately  11,000  different 
pitches. 

1  V  D  means  double  or  complete  vibrations. 

^  Philosophische  Studien,  4,  511  S. 

3  Zeitschr.  f.  Psychol,  u.  Phys.  d.  Sinnesorg.  16,  352  S. 


144        FUNDAMENTALS   OF  PSYCHOLOGY 

The  Octave.  —  Within  the  range  of  audible  tones  there 
seem  to  be  critical  points  similar  in  a  way  to  the  critical 
points  in  the  spectrum.  In  the  sound  series  these  critical 
points  are  the  octaves  of  the  musical  scale.  The  octave 
corresponds  to  the  spectrum.  As  one  may  say  that  the 
ends  of  the  spectrum  are  more  similar  than  the  middle  to 
either  end,  so  double  the  vibration  of  any  tone  gives  a  note 
that  is  more  similar  to  it  in  one  respect  than  the  intermediate 
tones.  These  octaves  constitute,  for  the  trained  ear  at 
least,  regularly  recurring  similar  tones.  Within  the  octave 
the  notes  whose  vibration  rates  form  a  ratio  of  2:3,  3:4,  4:5, 
etc.  with  the  lower  note  of  the  octave  constitute  other 
marked  resting  points  or  qualities  which  are  recognized  at 
once  by  the  musically  trained.  Trained  ears  are  more  likely 
to  make  a  mistake  of  an  octave  in  the  note  than  to  mis- 
take one  note  for  another  within  the  octave.  This  may 
possibly  be  due  to  special  training,  as  many  other  systems 
of  music,  the  Chinese,  for  example,  seem  not  to  recognize 
the  same  distinctions,  but  the  balance  of  evidence  at  present 
seems  to  favor  the  view  that  the  distinction  is  fundamental. 

Tone-color.  —  Two  other  differences  in  the  quahty  of 
tones  may  be  mentioned.  One,  that  tones  of  the  same 
pitch  from  different  instruments  have  a  characteristic  dif- 
ference ordinarily  spoken  of  as  timbre  or  tone-color,  which 
depends  upon  the  overtones  that  are  added  to  the  funda- 
mental. Thus  in  the  C  of  64  double  vibrations  from  a 
piano  string  there  are  also  found  the  c  of  128,  the  g  of  192, 
the  c'  of  256,  the  e'  of  320,  the  g'  of  384,  the  seventh  over- 
tone of  448  which  does  not  correspond  exactly  with  any  note 
in  the  scale,  the  c"  of  512,  etc.  Every  multiple  of  the  rate 
of  vibration  of  the  fundamental  is  represented,  theoretically, 
since  they  correspond  to  the  nodes  in  which  the  sounding 
body  vibrates,  and  these  nodes  are  formed  at  each  small 


SENSATIONS   OF  TONE  145 

fraction  of  the  length  of  the  surrounding  body.  The 
first  ten  overtones  can  be  readily  heard  when  intensi- 
fied by  resonators.  If  one  will  hold  down  a  key  on 
the  piano  that  corresponds  to  one  of  the  overtones,  one 
can  hear  that  overtone  continue  to  vibrate  after  the  funda- 
mental has  been  dampened  by  dropping  the  key.  It  is 
started  into  vibration  by  resonance  and  continues  to  vibrate 
for  a  time  after  its  excitant  has  stopped.  With  practice 
one  can  hear  the  overtones  separately  with  the  unaided  ear. 
Each  instrument  has  its  own  arrangement  of  overtones,  and 
these  give  it  its  timbre.  The  tuning  fork  has  almost  none; 
in  the  piano  they  are  present  in  fairly  even  strength,  while 
in  the  violin  certain  of  the  high  ones  are  emphasized  at  the 
expense  of  the  lower.  Each  of  the  musical  instruments 
owes  its  pecuHar  quality  to  the  number,  pitch,  and  relative 
strength  of  its  overtones. 

Vowel  Qualities.  —  The  characteristic  differences  of 
vowels  can  be  given  a  similar  explanation.  Helmholtz  and 
Konig  believed  that  they  were  due  to  the  presence  or 
absence  of  overtones.  The  overtones  were  emphasized  by 
the  resonance  of  the  mouth  chamber  which  is  changed  in 
shape  by  the  contraction  of  certain  muscles.  This  supposi- 
tion was  confirmed  by  synthetizing  vowels,  —  for  example, 
by  putting  together  simple  tones  to  constitute  the  funda- 
mental with  its  overtones.  Recently  there  has  been  revived 
by  Kohler  ^  an  old  theory  of  Hermann  that  vowels  are  not 
due  to  the  presence  of  overtones  of  the  fundamental  note 
of  the  tone,  but  that  the  characteristic  of  the  vowel  was  some 
single  note  which  does  not  change  with  the  pitch  of  the 
fundamental,  as  would  be  necessary  if  it  were  an  overtone. 
These  characteristic  notes  were  called  formants  by  Her- 
mann and  were  assumed  to  be  developed  by  the  air  blown 
1  Kohler,  Zeitschrift  f.  Psychologic,  vol.  54,  p.  280. 


146        FUNDAMENTALS   OF  PSYCHOLOGY 

through  the  mouth  cavity,  which  is  given  a  different  form 
for  each  vowel.  Kohler  tested  a  number  of  individuals  by 
giving  them  a  series  of  tones  which  could  be  gradually 
changed  and  asking  them  to  say  when  the  tone  took 
on  a  vowel  or  consonant  character.  His  results  indicated 
that  the  vowels  were  about  an  octave  apart  through 
the  scale.  In  order  he  gives  the  following  notes  as  the 
characteristic  tones  of  vowel  sounds:  m  =  130,  u  =  260, 
0  =  520,  a  =  1040,  e  =  2080,  i  =  4100,  5  =  8200, 
/  =  17,000,  ch  =  34,000.  All  the  values  are  approximate 
only  and  the  sounds  are  the  sounds  of  the  German  letters. 
Between  the  pure  vowels  are  mixed  ones.  One  shades 
gradually  over  into  the  other  and  both  elements  can  be  dis- 
tinguished. Dayton  C.  Miller,'  by  an  objective  method, 
found  some  of  these  notes  to  be  present  in  the  vowels  but 
not  all.  He,  however,  accepts  the  Helmholtz  overtone 
theory  of  vowels.  Not  only  does  this  theory  serve  to  ex- 
plain the  vowel  sounds,  but  it  explains  the  characteristic 
differences  in  the  series  between  the  octaves.  The  notes 
repeat  themselves  in  the  octaves,  and  the  beginning  of  the 
repetition  is  marked  by  the  change  from  one  vowel  tone 
to  another.  It  is  suggested  that  the  sensations  corre- 
sponding to  increased  vibration  rate  may  be  pictured  as  a 
spiral,  with  the  same  notes  over  each  other. 

Beats.  —  An  effect  of  combinations  that  is  purely  sensa- 
tional is  found  in  the  beat.  If  two  tones  of  approximately 
the  same  pitch  are  sounded  together,  there  is  heard  an 
alternate  increase  and  decrease  of  the  tone  which  comes  as 
many  times  a  second  as  the  difference  in  the  number  of 
vibrations  per  second  of  the  component  tones.  Physically 
this  is  due  to  the  fact  that  the  component  tones  will  be 
alternately  in  the  same  phase  and  in  opposite  phases.    When 

1  Dayton  C.  Miller,  Science  of  Musical  Sounds,  pp.  219-243. 


SENSATIONS   OF  TONE  147 

they  are  in  the  same  phase,  the  resultant  will  be  the  sum, 
when  in  opposite  phases,  the  difference,  of  the  two  tenden- 
cies to  vibrate.  When  these  alternations  come  some  dis- 
tance apart,  they  are  heard  as  distinct  swellings  and 
diminutions;  when  closer  together,  merely  as  a  roughness 
of  the  tone.  For  the  theory  it  is  interesting  to  note  that 
most  beats  seem  to  be  carried  by  neither  of  the  tones 
themselves,  but  by  a  tone  intermediate  between  the 
tones  that  produce  the  beats.  This  we  must  come  back 
to  later. 

Tonal  Fusion.  —  Of  the  various  phenomena  that  were 
mentioned  in  connection  with  vision,  some  are  also  to  be 
noticed  in  sound.  The  phenomena  of  mixture  of  colors  is 
replaced  by  fusion  of  tones.  The  two  are  not  easily  com- 
parable, since  the  result  of  the  combination  of  tones  is 
dependent  upon  the  position  of  the  notes  within  the  octave 
also.  Each  note  in  a  fusion  can  with  a  little  practice  be 
heard  separately;  there  is  no  fusion  that  gives  an  intermedi- 
ate tone  as  in  color,  and  no  cancellation,  no  phenomenon 
allied  to  complementariness.  The  degree  of  fusion  of  the 
whole  depends  in  large  measure  upon  the  ratio  of  vibration 
rates  of  the  two  tones;  the  smaller  the  numbers  that  repre- 
sent the  ratios,  the  closer  the  fusion.  The  best  fusion  is  fur- 
nished by  the  octave,  whose  components  give  a  vibration 
rate  of  i  :  2,  the  fifth,  2  13,  and  decreases  with  the  ratios 
represented  by  larger  numbers  as  the  second,  8:9;  the 
seventh,  8  :  15,  etc.  This  relation  holds  at  least  approxi- 
mately, although  critics  have  insisted  that  the  degree  of 
fusion  in  certain  combinations  does  not  correspond  accu- 
rately to  the  smallness  of  the  numbers  that  express  the  ratio 
of  vibration  rates.  Closely  related  to  fusion  is  consonance 
or  the  availabiHty  of  the  combinations  for  musical  effects. 
This  depends  partly  upon  the  degree  of  fusion,  more  upon 


148        FUNDAMENTALS   OF  PSYCHOLOGY 

the  training  of  the  hearer.  This  dependence  upon  training 
is  shown  by  the  difference  in  what  is  regarded  as  pleasant 
between  occidental  and  oriental  music  and  in  the  gradual 
change  in  the  accepted  intervals  in  western  music.  The 
tritone,  the  fourth,  and  the  fifth,  the  only  intervals  used 
by  the  Greeks,  have  gradually  given  way  to  the  thirds  and 
sixths,  and  now  we  see  seconds  and  sevenths  admitted  to 
music  under  certain  circumstances.  It  is  the  feeling  tone, 
as  well  as  the  physical  combinations,  that  determines  the 
effect. 

Helmholtz  Theory  of  Consonance.  —  An  explanation  of 
consonance  is  given  by  Helmholtz  on  the  basis  of  beats. 
The  notes  that  give  the  most  perfect  fusion  are  themselves 
far  enough  apart  not  to  beat  and,  furthermore,  do  not  give 
rise  to  beats  between  their  overtones.  Thus  the  fifth  with 
a  ratio  of  vibrations  of  2  :  3  would  have  as  overtones  of 
the  first  components  4,  6,  8,  10,  etc.,  and  as  overtones  of 
the  second  component  6,  9,  12,  etc.  Of  the  first  four  over- 
tones only  the  8  and  9,  9  and  10  would  be  near  enough  to 
beat  or  be  dissonant,  and  two  of  the  first  four  would  be 
identical,  the  others  no  less  consonant  than  the  fundamen- 
tals themselves.  On  the  other  hand,  the  major  seventh, 
with  a  ratio  of  8  :  15,  while  giving  no  beats  between  the 
fundamentals,  would  have  beats  between  most  of  the  over- 
tones. The  fundamental  of  the  higher,  15,  would  beat  with 
the  first  overtone  of  the  second,  16,  the  third  overtone  of 
the  lower  beats  with  the  first  of  the  higher,  and  in  general 
there  are  many  beating  overtones  and  no  identical  ones 
below  the  eighth  of  one  and  the  fifteenth  of  the  other.  In 
general,  then,  dissonant  chords  may  have  beats  either  be- 
tween the  fundamentals  or  the  overtones,  while  consonant 
chords  have  few  beats  if  any  between  either  fundamentals 
or  overtones. 


SENSATIONS   OF  TONE  149 

After-sensations.  —  Like  colors,  tones  have  after-sensa- 
tions, but  only  positive  ones.  It  requires  some  time  for  a 
tone  to  reach  its  maximum,  and  also  it  persists  some  little 
time  after  the  physical  excitation  ceases.  The  ear  is  much 
more  rapid  in  its  adaptations  than  the  eye,  however;  it 
has  much  less  inertia.  According  to  Mayer  separate  tones 
can  be  heard  if  they  are  repeated  as  frequently  as  27  per 
second  for  notes  of  64  V  D  and  204  times  per  second  for  a 
note  of  1024.  There  are  also  intermittent  after-sensations 
of  tones,  but  they  are  not  so  often  noticed  as  after-images. 
Urbantschisch  reports  that  single  primary  after-tones  may 
last  from  one  to  ten  seconds.  The  intermittent  after-images 
may  follow  each  other  at  irregular  intervals  for  one  to  two 
minutes.  Each  after-sensation  will  last  from  10  to  15 
seconds  at  intervals  of  from  10  to  20  seconds.  Usually 
these  intermittent  tones  are  of  the  same  pitch  as  the  objec- 
tive tone,  but  some  may  be  higher  or  lower.  They  are 
fainter  than  the  original  and  usually  fluctuate  in  intensity. 

Corresponding  to  color  bhndness  are  rare  cases  of  what 
are  called  tone  islands,  —  the  patients  deaf  to  large  portions 
of  the  scale  who  can  hear  notes  of  intermediate  pitch.  More 
frequent  are  individuals  whose  range  of  audition  is  short- 
ened above  and  below,  and  it  is  a  fairly  general  rule  that 
the  upper  notes  gradually  cease  to  be  heard  with  increased 
age. 

Combination  Tones.  —  An  interesting  phenomenon  of 
hearing  is  furnished  by  combination  tones.  When  two 
notes  are  sounded,  one  frequently  hears,  in  addition  to  the 
notes  themselves,  tones  that  correspond  to  the  difference 
between  their  vibration  rates  or  to  the  sum  of  their  vibra- 
tion rates.  Thus  if  the  tones  c  and  e  of  128  and  160  be 
sounded  together,  one  will  hear  a  note  corresponding  to 
the  difference  in  their  vibration  rates,  32.     One  can  also 


I50        FUNDAMENTALS   OF  PSYCHOLOGY 

hear  a  second  difference  tone  whose  rate  is  the  difference 
in  rate  between  the  higher  and  twice  the  lower  (2  1  —  h) 
of  96  and  a  third  tone  (3  1  —  2  h)  of  64.  Some  authorities 
report  that  they  hear  fourth  and  fifth  difference  tones  named 
on  the  analogy  of  the  last.  The  striking  aspect  of  these 
tones  is  that  in  part  at  least  they  are  subjective;  they  can- 
not be  heard  more  clearly  by  means  of  resonators  than  by 
the  unaided  ear,  and  all  other  means  of  demonstrating  their 
objective  existence  fail.  They  must  apparently  be  ac- 
counted for  by  the  physiological  or  psychological  theory 
of  hearing.  Another  combination  tone  is  the  summation 
tone.  This  is  a  note  that  corresponds  to  the  sum  of  the 
vibration  rates  of  the  component  tones.  It  is  not  so  easy 
to  hear  as  the  difference  tones,  and  it  is  more  difficult  to 
obtain  pure  conditions  for  it,  as  in  many  cases  it  will  corre- 
spond to  an  overtone  or  to  a  difference  tone  between  the 
overtones.  The  summation  tones  are  probably  of  subjective 
origin,  but  no  satisfactory  explanation  has  been  given  of 
how  they  originate. 

Tone  and  Noise.  —  The  other  even  more  fundamental 
difference  in  sounds  is  that  which  obtains  between  tones 
and  noise.  The  difference  is  sufficiently  famiHar  to  need  no 
description.  Physically  as  well  as  psychologically  two  forms 
of  noise  are  to  be  distinguished.  The  more  usual  is  due  to 
a  very  complex  mass  of  tones  that  have  no  simple  relation 
in  their  vibration  rates,  and  have  even  been  said  to  be  non- 
pendular  in  character.  Any  inharmonious  combination  of 
many  tones  is  accepted  as  noise.  A  noise  of  this  kind  passes 
gradually  over  into  tone,  as  the  degree  of  dissonance  is 
lessened,  or  the  tonal  element  comes  to  predominate.  If 
there  are  any  tones  that  are  not  reducible  to  the  ordinary 
pendular  or  sine  form,  they  may  also  be  present  in  noise. 
That  complex  sounds  Uke  the  sawing  of  wood  or  the  rattle 


THEORIES   OF  HEARING  151 

on  a  city  street  are  merely  tones  in  great  number  and  variety 
without  any  harmonic  relation  is  probable,  since  with  reso- 
nators one  can  distinguish  tonal  elements  in  them.  The 
second  type  of  noise  corresponds  to  a  simple  vibration  too 
short  to  produce  the  full  tonal  character.  Upon  cutting 
off  a  pure  tone  after  only  one  or  two  full  vibrations  have 
been  made,  a  sudden  noise  is  heard,  which  lacks  the  tonal 
character.  This  is  usually  done  by  passing  the  tone  through 
a  tube  that  can  be  opened  to  permit  the  sound  to  pass  for 
only  a  fraction  of  a  second.  When  less  than  two  full  vibra- 
tions reach  the  ear,  the  effect  is  a  shock.  The  full  tonal 
character  of  the  sound  is  obtained  only  when  sixteen  full 
vibrations  are  heard.  Noise  and  tone,  then,  are  different 
only  in  the  time  of  stimulation  or  in  the  arrangement  or 
combination  of  the  elementary  waves,  not  in  the  character 
of  the  waves  themselves. 

Theories  of  Hearing.  —  The  physiological  theory  can 
be  discussed  only  in  connection  with  the  structures  about 
the  endings  of  the  auditory  nerve  in  the  cochlea.  As  was 
said,  the  auditory  nerve  enters  the  centre  of  the  modiolus 
about  which  the  cochlear  canal  is  wound,  and  the  sheet  of 
fibres  extends  through  the  lamina  spiralis  to  end  in  the 
neighborhood  of  hair  cells  on  the  basilar  membrane.  The 
structures  here  are  somewhat  complicated,  but  the  theories 
have  made  no  use  of  most  of  the  complications.  The  mem- 
brane that  helps  to  divide  the  cochlea  into  two  canals  con- 
sists in  large  part  of  transverse  fibres.  These  for  Helmholtz 
constitute  the  essential  part  of  the  basilar  membrane.  Be- 
low them  is  a  layer  of  connective  tissue  which  is  thicker 
than  the  layer  of  fibres.  On  the  basilar  membrane  are  found 
several  pecuHar  structures.  The  most  striking  of  these  are 
the  rods  of  Corti.  These  consist  of  two  rows  of  dehcate 
structures  curved  and  fitted  together  at  the  top  to  form  a 


152        FUNDAMENTALS   OF  PSYCHOLOGY 

clearly  defined  arch.  They  leave  an  opening  between 
them,  the  canal  of  Corti.  These  rods  are  not  continuous 
longitudinally  and  are  considerably  less  numerous  than  the 
fibres  of  the  basilar  membrane.  On  the  inner  side  of  the 
arch  is  one  layer  of  cells  with  a  tuft  of  hair  at  the  top;  on 
the  outer  side  are  four  or  five  layers,  with  similar  tufts  that 
extend  through  a  membrane,  Kohiker's  membrane,  to  the 
lymph  of  the  cochlear  canal.  Covering  the  outer  portion 
of  the  basilar  membrane  are  relatively  thick  epithehal  cells. 

d     f     9       h        i 


Fig.  ss. — Organ  of  Corti.  h,  basilar  membrane;  d,  outer  auditory  or  hair  cells; 
s,  inner  auditory  cell:  /,  top  of  outer  rod  of  Corti,  forming  one  side  of  the  arch  of 
Corti;  o,  inner  pillar  cell;  g,  tectorial  membrane;  q,  nerve  fibres;  n,  nerve  fibres 
extending  across  the  canal  of  Corti.    (From  Huber  after  Retzius  ) 

On  the  inner  side,  extending  out  from  and  well  above  the 
lamina  spiralis,  is  a  delicate  membrane,  the  tectorial  mem- 
brane, which  hangs  free  in  the  liquid  above  the  entire  width 
of  the  differentiated  mechanisms.  These  can  all  be  made 
out  in  Figure  55. 

On  first  sight  one  would  think  that  the  rods  of  Corti  must 
be  the  essential  organ  of  hearing.  They  are  so  highly 
developed  and  delicate  that  a  teleologist  would  insist  that 
they  must  have  some  specific  function. 

The  most  fully  developed  theory  is  that  of  Helmholtz. 
In  essentials  it  assumes  that  there  must  be  in  the  ear 
resonators  tuned  to  each  tone  heard.    An  analogy  can  be 


THEORIES   OF  HEARING  153 

drawn  with  the  piano  strings  which  vibrate  in  sympathy 
with  the  tones  that  are  present  in  the  outer  air.  If  one 
speaks  in  a  room  with  a  piano,  the  tones  of  the  voice  will 
be  heard  sounding  after  the  voice  has  ceased.  If  one  will 
hold  down  a  key  and  sing,  the  corresponding  note  will  be 
distinctly  heard  to  respond  in  sympathetic  vibration. 
Helmholtz  beheved  that  there  must  be  resonators  in  the  ear 
which  respond  in  the  same  way  to  the  vibration  for  which 
they  are  tuned.  His  first  idea  was  that  the  arches  of  Corti 
must  be  these  organs.  When  they  were  counted,  however, 
it  was  found  that  there  were  only  3000  of  them,  while  it  was 
known  that  some  1 1 ,000  tones  could  be  heard.  Helmholtz 
then  turned  for  his  resonators  to  the  fibres  of  the  basilar 
membrane.  These  are  sufficiently  numerous  (18,000- 
24,000)  to  provide  a  resonator  for  each  tone  that  can  be  heard. 
They  also  show  some  difference  in  length,  —  at  the  upper 
end  of  the  cochlea  they  are  approximately  0.48  mm.  long, 
at  the  lower  end  about  0.04.  This  is  not  difference  enough 
to  account  for  the  difference  in  pitch  that  they  are  supposed 
to  show,  but  Helmholtz  assumed  that  they  were  differently 
loaded  and  tuned  by  that  means  for  the  different  tones. 

In  the  completed  theory,  then,  it  was  assumed  that  in  the 
basilar  membrane  are  fibres,  or  really  sections  of  the  mem- 
brane, tuned  to  each  note  heard.  The  various  complex  vibra- 
tions are  impressed  upon  the  Hquid  of  the  inner  ear  by  the 
oscillations  of  the  stirrup,  and  these  are  analyzed  into  their 
parts  by  the  fibres.  In  a  piano  tone,  or  other  note  rich  in 
overtones,  a  separate  fibre  is  set  into  vibration  by  the 
fundamental  and  by  each  of  the  overtones;  in  a  chord  each 
component  similarly  arouses  a  different  fibre  or  group  of 
fibres  and  each  is  sent  to  the  centres  by  a  separate  nerve. 
The  vibrations  of  these  fibres  serve  in  some  way  not  made 
very  clear  to  stimulate  the  nerve  fibres  between  the  hair 


154        FUNDAMENTALS   OF  PSYCHOLOGY 

cells.  The  vibration  of  the  fibres  is  dampened  by  the  tec- 
torial membrane,  which  is  assumed  to  drop  down  upon 
them  when  the  sound  ceases.  Noises  were  at  first  assigned 
to  the  vestibular  structures,  but  when  these  were  discovered 
to  have  another  function,  they  too  were  regarded  as  due  to 
excitations  of  many  fibres  in  the  basilar  membrane.  In- 
direct evidence  was  found  to  support  the  theory  in  the  fact 
that  in  cases  of  deafness  to  part  of  the  scale,  parts  of  the 
basilar  membrane  were  likely  to  be  diseased.  Von  Bezold 
has  found  that  patients  who  have  the  so-called  tone  islands, 
parts  of  the  scale  that  they  can  hear,  while  deaf  to  most 
notes,  also  are  found  after  death  to  have  lesions  in  the  cor- 
responding part  of  the  basilar  membrane.  In  the  aged  the 
lower  part  of  the  basilar  membrane  is  often  in  a  pathological 
condition,  and  they  fail  to  hear  high  tones. 

Details  of  Helmholtz's  Theory.  —  The  theory  is  adapted 
to  explain  a  number  of  the  facts  of  hearing.  Beats  may 
be  regarded  as  due  to  an  overlapping  of  the  vibrating 
portions  of  the  membrane,  and  thus  as  giving  rise  to  an  in- 
terference phenomenon  in  the  intermediate  fibres.  On  this 
assumption  each  tone  would  cause  a  ribbon  of  several  fibres 
to  vibrate  instead  of  a  single  fibre  as  Helmholtz  first  as- 
serted. When  they  were  near  together,  the  outer  edges 
of  the  two  ribbons  would  have  common  fibres.  These  would 
tend  to  vibrate  with  the  rates  of  both  notes,  and  the  inter- 
ference of  the  two  movements  would  cause  the  beats.  This 
view  receives  support  from  the  fact  mentioned  earher  that 
it  is  a  note  intermediate  between  the  other  two  that  beats 
rather  than  either  of  the  component  tones.  It  is  the 
intermediate  fibres  that  are  vibrating  at  two  different  rates 
and  consequently  carry  the  beats.  When  the  vibrating 
ribbons  are  sufficiently  far  apart  there  are  no  interferences 
and  so  no  beats. 


THEORIES   OF  HEARING  155 

The  explanation  of  difference  tones  is  not  so  satisfactory. 
Helmholtz  at  first  thought  they  might  be  beat  tones,  misled 
by  the  fact  that  there  would  be  as  many  beats  per  second 
as  the  vibrations  per  second  of  the  difference  tones.  This 
was  given  up  when  it  was  seen  that  the  beats  could  not  stim- 
ulate the  corresponding  fibre  in  the  basilar  membrane.  His 
final  explanation  was  that  they  must  be  produced  in  the 
middle  ear.  He  demonstrated  by  a  differential  equation 
that  a  membrane  loaded  on  one  side  alone  when  excited 
simultaneously  by  two  rates  of  vibration  should  produce  a 
third  vibration  that  corresponds  in  its  rate  to  the  difference 
between  the  rates  of  the  two  components,  but  he  did  not 
point  out  the  physical  correlates  of  his  mathematical 
values. 

On  the  whole  the  Helmholtz  theory  is  the  most  detailed; 
it  accounts  for  more  facts  than  the  others  and  receives  more 
incidental  support.  Its  weakness  is  a  conflict  with  the 
anatomical  findings.  The  basilar  membrane  does  not  con- 
sist of  a  series  of  delicate  fibres  hanging  relatively  free  and 
separated  from  each  other.  Instead,  the  fibres  are  em- 
bedded in  a  mass  of  tissue  on  both  sides  thicker  than  the 
fibres  themselves.  Ayres  tested  the  possibility  of  the 
basilar  membrane's  vibrating  to  tones  on  the  ear  of  a  crimi- 
nal who  had  just  been  executed,  and  found  that  even  with 
this  perfectly  fresh  material  and  the  most  favorable  condi- 
tions no  vibration  in  the  basilar  membrane  could  b2 
detected. 

Telephone  Theories.  —  Other  theories  abandon  the 
resonator  principle,  assuming  instead  that  some  structure 
in  the  cochlea  must  vibrate  as  a  whole  and  the  analysis  of 
the  separate  tones  be  made  by  the  cortical  centres.  Hensen 
and  Rutherford  have  assumed  that  the  basilar  membrane, 
acting  much  hke  the  plate  of  a  telephone,  transmits  the 


156         FUNDAMENTALS   OF  PSYCHOLOGY 

complex  notes  to  the  cortex  where  analysis  takes  place. 
Max  Meyer  has  a  somewhat  similar  theory.  His  assump- 
tion is  that  the  intensity  of  the  tone  is  determined  by  the 
distance  the  vibration  extends  inward  from  the  oval  win- 
dow, while  the  quahty  is  determined  by  the  rate  of  vibration 
of  the  membrane  as  a  whole.  Hardesty^  has  abandoned  the 
basilar  membrane  as  the  vibrating  mechanism  and  assumes 
that  the  tectorial  membrane  is  the  receiving  organ.  Har- 
desty  argues  that  the  vibrations  of  the  liquid  are  taken  up 
by  the  tectorial  membrane  and  communicated  to  the  hair 
cells  and  thence  carried  to  the  brain,  where,  as  in  the  other 
theories  of  this  type,  analysis  takes  place.  The  difficulty 
with  this  whole  group  of  theories  Hes  in  the  assumption  that 
differences  in  vibration  rate  so  slight  as  one  in  ten  thousand 
should  be  appreciated  by  the  cortex,  while  the  most  delicate 
appreciation  of  differences  in  intensities  is  one  in  a  hundred. 
The  difference  in  intensity  that  can  be  appreciated  by  the 
ear  is  only  one  in  live.  On  teleological  grounds,  which  of 
course  have  Httle  weight,  it  seems  inexphcable  that  the 
extension  of  the  auditory  nerve  over  such  a  wide  area  with 
relatively  compHcated  end  organs  should  have  no  particular 
function. 

It  can  be  seen  that  in  spite  of  the  ingenuity  and  assiduity 
of  investigators  and  theorists,  a  satisfg^ctory  theory  of 
hearing  is  yet  to  be  developed.  The  Helmholtz  theory  has 
the  advantage  of  all  the  others  in  the  number  of  facts  that 
it  explains  and  the  detailed  nature  of  its  explanation;  it 
suffers  from  the  improbability  of  its  demand  that  the 
fibres  of  the  basilar  membrane  vibrate  separately.  On  the 
other  hand,  the  theories  that  give  a  plausible  explanation 
of  the  way  the  anatomical  structures  may  act  make  large 

1  Hardesty:  On  the  Nature  of  the  Tectorial  Membrane,  etc.  American 
Journal  of  Anatomy,  Vol.  VIII,  p.  109. 


CUTANEOUS   SENSATIONS  157 

demands  on  our  ability  to  distinguish  differences  between 
vibration  rates. 


REFERENCES 

Watt:  The  Psychology  of  Sound. 

Ladd-Woodworth  :     Elements    of    Physiological    Psychology, 

pp.  196-208. 
Myers:  Experimental  Psychology,  Chs.  III-IV. 
Howell:  Physiology,  Ch.  XX. 

Helmholtz:  Sensation  of  Tone.     Tr.  Ellis,  2d  edition. 
Schaefer:  Der  Gehorsinn,  Nagel's  Handbuch  der  Physiologic, 

Vol.  Ill,  pp.  476-588. 


Tactual  Sensations 

Cutaneous  Sensations.  —  The  sensations  from  the  skin 
are  simplest  of  all,  and  their  organs  are  most  accessible, 
but  only  in  the  present  generation  have  the  more  important 
facts  concerning  them  been  cUscovered.  The  same  dis- 
tinctions between  physical  stimulus,  physiological  processes, 
and  sensations,  that  we  have  been  compelled  to  make  in  the 
other  senses  are  to  be  drawn  here.  The  adequate  stimuh 
for  the  skin  are  mechanical  and  thermal.  But  while  the 
stimuh  vary  only  in  intensity,  different  sense  organs  are 
affected  by  different  intensities,  and  corresponding  differ- 
ences in  sensation  result.  This  is  most  marked  in  the  tem- 
perature sense.  The  physicist  assures  us  that  cold  is  nothing 
positive,  but  merely  a  reduction  in  the  amount  of  heat. 
Nevertheless  when  the  temperature  is  reduced  below  about 
30°  C.  a  sense  organ  is  excited  which  gives  rise  to  the  sensa- 
tion of  cold,  and  this  sensation  increases  as  the  tempera- 
ture is  lowered.  Above  30°  another  organ  is  stimulated  and 
its  activity  increases  as  the  temperature  rises.  Similarly, 
shght   mechanical   stimuh   excite   sensations   of    pressure; 


158        FUNDAMENTALS   OF   PSYCHOLOGY 

and  intense  ones,  sensations  of  pain.  We  then  have  four 
distinct  sense  quahties,  while  there  are  but  two  kinds  of 
physical  stimulus.  More  clearly  than  in  any  other  organ 
can  the  sense  quahties  be  shown  to  depend  upon  the  organ 
stimulated. 

Temperature 

The  discovery  of  the  distribution  of  the  organs,  and  with 
that  the  settlement  of  most  of  the  problems  of  cutaneous 
sensibihty,  is  a  matter  of  comparatively  recent  date.  It 
came  first  in  the  temperature  senses.  At  approximately 
the  same  time  and  altogether  independently  of  each  other 
three  investigators,  Blix,  a  Scandinavian  (1882),  Gold- 
scheider,  a  German,  and  Donaldson,  an  American  (both 
1885),  found  that  the  skin  was  sensitive  to  temperature 
only  in  relatively  isolated  spots  rather  than  all  over,  as  had 
been  earUer  supposed.  The  skin  was  carefully  tested  point 
by  point  with  a  cooled  or  heated  metal  point,  and  it  was 
found  that  at  certain  points  irregularly  arranged  one  would 
feel  cold,  at  others,  warmth.  The  most  important  disagree- 
ment in  the  results  found  was  between  Goldscheider  on  the 
one  side  and  Blix,  with  practically  all  later  workers,  on  the 
other.  Goldscheider  found  warm  and  cold  points  to  be 
thickly  scattered  everywhere  on  the  skin;  for  example,  on 
the  back  of  the  hand  there  were  68  cold  spots  and  56  warm 
spots  on  a  square  centimetre.  BHx  reported  that  they  were 
much  farther  apart,  and  all  later  investigators  have  con- 
firmed his  results.  Sommer  counted  carefully  the  number 
in  many  square  centimetres  and  found  that  there  were  from 
6  to  24  cold  spots,  and  from  o  to  3  warm  spots,  to  the  square 
centimetre.  He  gave  as  his  average  12  to  13  cold  and  i  to 
2  warm  spots.  His  estimate  for  the  whole  body  was  250,000 
cold  and  30,000  warm  spots. 


CUTANEOUS   SENSATIONS 


59 


Indirect  Evidence  of  the  Existence  of  Warm  and  Cold 
Spots.  —  Many  of  the  earlier  theories  assumed  that  there 
must  be  a  single  organ  for  warmth  and  cold.  Hering,  for 
example,  had  a  theory  which  would  make  warm  and  cold 
depend  upon  assimilation  and  dissimilation  in  the  single 


.     -V 


Fig.  s6.  —  Map  of  temperature  spots  on  volar  surface  of  the  forearm.  The  dots 
represent  warm  spots  as  tested  at  a  temperature  of  41-48°  C;  the  crosses,  cold 
spots  tested  at  10°.    (From  Howell  after  von  Frey.) 

organ,  in  very  much  the  same  way  that  his  complementary 
colors  depended  upon  those  processes  in  the  single  color 
organ.  It  was  therefore  essential  when  the  spots  were  first 
mapped  to  prove  by  other  evidence  that  the  spots  were 
distinct.  Certain  characteristic  differences  in  the  way  the 
two  organs  respond  and  in  the  substances  that  stimulate 
them  provided  this  evidence,     i.  It  takes    considerably 


i6o        FUNDAMENTALS   OF  PSYCHOLOGY 

longer  to  stimulate  the  warm  spots  than  the  cold  spots,  per- 
haps an  evidence  that  the  former  are  farther  from  the  sur- 
face. 2.  Certain  inadequate  stimuli  will  affect  one  but  not 
the  other.  Cold  is  particularly  easy  to  excite  by  induction 
currents,  by  pressure,  or  even  by  heat.  Menthol  stimulates 
the  cold,  carbon  dioxide  the  warm  organs.  3.  There  are 
certain  larger  areas  of  the  body  in  which  only  one  sort  of 
sensation  will  be  found.  Thus  on  the  cornea  and  con- 
junctiva of  the  eye  cold  alone  is  felt,  warmth  is  lacking 
altogether.  That  there  are  different  organs  for  cold  and 
for  warmth  is  not  now  disputed. 

The  Temperature  Scale.  —  The  more  detailed  relation 
between  the  physical  temperature  and  the  sensations  that 
result  from  the  stimulation  may  be  given.  The  critical 
point  for  most  purposes  is  the  so-called  physiological  zero 
point  that  separates  cold  from  warm.  This  point  varies 
much  with  the  temperature  to  which  the  skin  has  been 
adapted.  For  a  covered  part  of  the  body,  it  is  apparently 
in  the  neighborhood  of  from  28°  to  30°  C;  on  the  back  of 
the  hand,  it  has  been  found  to  vary  between  23°  and  ;^;^°, 
and  after  the  hand  has  been  immersed  in  water  at  11°  for 
some  time,  water  at  12°  seems  warm,  and  it  may  similarly 
be  adapted  for  temperatures  of  39°.  The  width  of  the  in- 
difference point  seldom  is  greater  than  0.5°.  If  we  assume 
an  indifference  point  at  30°  C,  below  it  the  cold  spots  alone 
are  stimulated  to  somewhere  in  the  neighborhood  of  10°, 
where  pain  is  added  to  the  complex.  Above,  one  obtains 
warmth  alone  up  to  45°.  Here  the  cold  spots  are  excited  in 
addition  to  the  warmth,  and  the  combination  gives  hot  as 
opposed  to  lukewarm.  This  excitation  of  the  cold  organ 
by  a  hot  stimulus  gives  what  is  known  as  a  paradoxical  cold. 
The  fact  was  first  discovered  by  Alrutz  and  has  been  con- 
firmed by  von  Frey.    One  experiment  performed  by  Alrutz 


CUTANEOUS   SENSATIONS 


i6i 


was  to  fatigue  the  warm  spots  in  the  foot  by  keeping  it 
immersed  for  some  time  in  warm  water  and  then  to  swing 
it  quickly  through  hot  water.  The  hot  water  then  seemed 
cold.  Above  50°  to  55°  the  sensation  of  burning  heat  makes 
its  appearance  as  a  consequence  of  the  mixture  of  pain  with 


_i       3:      ua 


Fig.  57.  —  Temperature  scale.  Shows  the  sense  organs  stimulated  and  the 
degree  of  stimulation  at  different  temperatures.  Figures  on  the  base  line  indicate 
the  temperature  in  centigrade,  the  height,  the  degree  of  stimulation.     (After  von 

Frey.) 

the  other  sensations.  The  question  naturally  arose  as  to 
whether  there  was  a  paradoxical  warmth  at  the  lower  ranges 
similar  to  the  paradoxical  cold.  The  burning  sensation 
after  long  exposure  to  cold  suggests  that  the  warm  spots 
might  be  stimulated.  Experiments  by  Alrutz  and  Thun- 
berg,  however,  gave  no  warrant  for  the  assumption.  The 
warm  or  hot  sensations  at  low  temperatures  are  probably 
due  to  the  mixture  of  sensations  of  pain  with  some  tinglings 


i62        FUNDAMENTALS   OF  PSYCHOLOGY 

due  to  changes  in  circulation.    Figure  57  shows  these  various 
phenomena  in  diagrammatic  form. 

Pressure  and  Pain 

Mechanical  Cutaneous  Sensations.  —  Very  much  the 
same  distinction  may  be  made  between  pressure  and  pain 
as  between  warmth  and  cold.  Goldscheider  also  discovered 
that  only  certain  points  on  the  body  would  respond  to  pres- 
sure. There  was  approximately  the  same  difference  of 
opinion  between  Goldscheider  and  the  others  as  to  the 
number  of  spots.  Goldscheider  found  many,  the  others 
relatively  few.  Von  Frey,  who  has  done  the  most  careful 
and  most  recent  work  on  the  pressure  sensations,  found  that 
there  are  from  o  to  300  per  square  centimetre.  On  the  whole 
body  surface,  excluding  the  head,  where  they  are  the  most 
numerous,  he  estimates  there  are  approximately  500,000. 
They  are  more  numerous  than  either  kind  of  temperature 
spots.  In  determining  their  position  von  Frey  used  fine 
hairs  mounted  on  matches  or  similar  small  bits  of  wood. 
These  gave  a  very  small  point  and  a  constant  pressure. 
Wherever  there  were  hairs  on  the  body  he  found  that  the 
pressure  spots  correspond  to  them.  They  are  also  found  on 
the  surfaces  free  from  hairs. 

Sensations  of  Pain.  —  Pain  has  been  even  more  in  dispute 
than  the  other  senses.  Until  von  Frey's'^  Work  in  1896  it 
had  usually  been  held  either  that  pain  was  a  feeling,  not  a 
sensation  at  all,  or,  if  it  was  a  sensation,  that  it  must  be 
regarded  as  due  merely  to  the  overstimulation  of  the  pres- 
sure organ.  Goldscheider  in  his  investigations  modified 
this  view  slightly.  Pain  stimuli  were  carried  to  the  spinal 
cord  by  the  same  neurons  as  pressure,  but  there  took  a  dif- 
ferent course.    While  the  pressure  sensation  continued  by 

'  Leipziger  Abhandlung,  1896 


CUTANEOUS  SENSATIONS  163 

the  same  neurone  up  the  posterior  columns,  the  intense 
impressions  were  supposed  to  force  a  way  across  a  synapse 
to  new  neurones  with  cells  in  the  central  gray  and  take 
another  path.  As  evidence  that  there  is  this  more  difficult 
path  through  the  central  gray,  Goldscheider  adduces  the 
long  time  required  to  receive  pain  sensations.  The  reaction 
time  for  pressure  is  from  o.i  2  to  0.2,  while  the  time  for  pain 
rises  to  0.6  to  0.8  second.  He  uses  this  theory  also  to  explain 
summation  pains  such  as  those  involved  in  the  Chinese 
water  torture,  in  which  drops  of  water  are  permitted  to  fall 
for  a  long  time  upon  the  same  point  until  the  successive 
slight  stimuli  give  rise  to  an  unbearable  pain.  The  summa- 
tion is  assumed  to  take  place  in  the  cells  of  the  cord.  Also 
the  effects  in  the  disease  syringomyelia  are  mentioned  as 
confirmatory  of  his  theory.  In  this  disease  an  infection 
extends  from  the  central  canal,  destroying  the  cells  in  the 
surrounding  gray  matter.  Patients  suffering  from  this 
disease  feel  only  pressure  and  cold  in  certain  areas  of  the 
skin,  but  have  no  sensations  of  pain  and  warmth.  Gold- 
scheider interpreted  this  to  mean  that  the  paths  for  pain 
were  destroyed,  while  the  paths  through  the  white  matter 
were  left  intact.  Goldscheider,  too,  explained  on  this 
theory  the  'referred  pains'  so  prominent  in  most  diseases. 
He  assumes  that  two  or  more  regions  of  the  body  are  con- 
nected with  the  same  cells  in  the  cord.  Thus  he  would  say 
that  the  mucous  membrane  of  the  stomach  and  the  skin 
of  the  back  were  connected  with  the  same  cells  in  the  cord. 
When  certain  disturbances  of  the  stomach  developed,  the 
excitation  of  its  nerves  would  be  carried  to  the  cells  in  the 
cord  that  give  rise  to  the  sensation  of  pain,  and  the  sensa- 
tion would  be  excited  in  the  cortex.  But  since  the  same  cells 
also  transmit  pain  impulses  from  the  middle  of  the  back, 
and  we  are  much  more  familiar  with  that  area,  the  pain 


1 64        FUNDAMENTALS   OF  PSYCHOLOGY 

would  be  referred  to  the  known  region,  the  back,  rather 
than  to  the  wall  of  the  stomach,  a  surface  never 
seen  and  where  voluntary  contact  has  never  produced 
pains.  A  somewhat  similar  theory  of  referred  pains  has 
been  given  by  Head^  without  accepting  the  other  portions 
of  Goldscheider's  theory. 

Pain  Spots.  —  More  recent  investigations  have  shown 
that  the  first  part  of  Goldscheider's  theory,  that  pain  and 
pressure  impulses  have  the  same  path  to  the  cord,  is  probably 
incorrect.  Von  Frey,  in  particular,  by  very  careful  mapping 
of  the  skin,  has  shown  that  there  are  special  pain  spots  in  the 
skin  in  addition  to  the  pressure  and  temperature  spots.  The 
mapping  was  on  an  enlarged  scale  diagram  of  the  small 
portion  of  the  skin  worked  with.  The  skin  was  explored 
with  a  sharpened  horse  hair  under  a  magnifying  glass,  and 
it  was  found  that  sensations  of  pain  were  given  only  at  cer- 
tain points,  mostly  in  the  small  lines  of  depression  on  the 
skin.  These  were  found  to  be  much  less  sensitive  than  the 
pressure  spots,  required  about  one  thousand  times  as  great 
a  pressure  to  stimulate  them,  and  were  much  more  numer- 
ous than  any  other,  on  the  average,  one  hundred  to  the 
square  centimetre.  It  was  estimated  that  there  are  between 
two  and  four  million  pain  spots  on  the  surface  of  the  body. 
Much  corroboratory  evidence  has  been  brought  to  confirm 
the  results  of  mapping  the  spots.  It  has  been  found  that 
there  are  some  parts  of  the  body,  the  conjunctiva  of  the 
eye,  for  example,  where  there  are  pain  spots  but  no  pressure 
spots;  others,  as  the  inner  hning  of  the  cheek,  where  there 
are  pressure  spots  but  no  pain  spots.  Another  bit  of  evi- 
dence depends  upon  the  slow  response  to  pain  mentioned 
above.  If  a  pressure  spot  be  stimulated  by  a  shght  alter- 
nating electric  current  with  alternations  of  fifty  or  sixty 

^  Brain,  1893. 


CUTANEOUS   SENSATIONS 


165 


Fig.  58.  —  Termination  of 
sensory  nerve-fibres  in  the 
mucosa  and  epithelium  of 
the  cat.    (From  Huber.) 


1 66 


FUNDAMENTALS   OF  PSYCHOLOGY 


per  second,  the  separate  alternations  will  be  noticed.  If, 
on  the  contrary,  the  current  be  applied  to  a  pain  spot, 
there  is  a  continuous  sharp  sensation. 

I 


Fig.  5q. — Nerve  endings  in  skin  and  about  hair  follicles,  c,  superficial  plexus  of 
fibres  in  skin  (free  nerve  endings  are  still  nearer  the  surface),  h,  the  hair  with 
nerves  about  root      (From  Barker,  after  Retzius.) 

Cutaneous  Sense  Organs.  —  The  sense  organs  for  these 
different   sensations  have  been  determined    with  varying 


CUTANEOUS   SENSATIONS 


167 


Fig.  60.  —  Tactile  cor- 
puscle of  Meissner  from  the 
skin  of  the  toe.  A'^,  nerve 
fibre.     (From  Barker.) 


degrees  of  certainty.  Pressure  spots  seem  closely  connected 
with  the  hairs  on  the  parts  of  the  body  where  there  are  hairs. 
The  spot  that  responds  is  always  just 
over  the  root  of  a  hair  (Fig.  59).  It 
is  probable  that  the  nerve  about  the 
root  is  stimulated  by  the  hair  which, 
as  it  is  bent,  acts  as  a  lever.  On  the 
surfaces  without  hairs,  the  palms 
and  soles  of  the  feet,  von  Frey  sug- 
gests that  the  Meissner  corpuscle  f. 
(Fig.  60)  is  the  organ.  Pain  spots 
are  ascribed  to  the  free  nerve  endings 
(Fig.  58).  These  come  closest  to  the 
surface  of  any  of  the  end  organs  in 
the  skin  and  the  sensations  of  pain 
are  aroused  by  the  most  superficial 
stimulations.  Acids  that  affect  only 
the  epidermis  give  pain  sensations  without  sensations  of 
pressure  or  temperature.  It  is  more  difficult  to  determine 
the  organs  for  temperature  and  the  results  are  less  trust- 
worthy. Following 
von  Frey  again,  we 
may  regard  the  end 
organs  of  Krause 
(Fig.  61)  as  the  sense 
organs  of  cold,  since 
they  with  the  free 
nerve  endings  are  the 
only  sense  organs  found  in  the  conjunctiva,  where  also 
only  pain  and  cold  can  be  felt.  Because  the  sensations  of 
warmth  seem  to  originate  well  below  the  surface  and  the 
organ  of  Ruffini  also  is  found  relatively  deep,  that  has  been 
regarded  as  the  sense  organ  of  warmth  (Fig.  62). 


End  bulb  of  Krause.     (From  Barker.) 


i68        FUNDAMENTALS   OF  PSYCHOLOGY 


Regeneration  of  Cutaneous  Sensations.  —  An  experi- 
ment performed  by  Head  and  Rivers  tends  to  establish  a 
second  classification  of  cutaneous 
sensations  that  has  not  been 
brought  into  complete  agree- 
ment with  the  one  given  above. 
They  cut  the  ulnar  nerve  where 
it  is  near  the  surface  at  the  elbow 
and  then  studied  the  sensations 
that  remained  and  the  gradual 
reappearance  of  sensations  as  the 
nerve  regenerated.  At  once, 
after  the  nerve  was  cut,  all  sen- 
sations from  the  skin  proper  dis- 
appeared. Neither  pressure  nor 
pain,  warmth  nor  cold,  could  be 
felt.  When  more  intense  stimu- 
lation was  appUed,  pressure  and 
pain  could  be  felt  from  the 
tissues  under  the  skin,  of  ap- 
proximately the  same  quahty  as 
from  the  normal  deeper  tissue 
in  the  arm.  This  they  call  the 
deeper  lying  sensibility.  After 
the  lapse  of  forty-three  days, 
sensations  first  began  to  return 
to  the  skin.  The  first  evidence 
of  regaining  sensation  was  in 
the  diminution  of  the  area  in- 
sensitive to  pain.  On  the  one 
hundred  twelfth  day  sensations  of  cold  made  their  appear- 
ance, and  the  area  sensitive  to  pain  had  much  increased. 
Nearly  two  months  later  the  hairs  were  found  to  be  sensi- 


FiG.    62.  —  End    organ   of   Ruffini. 
(From  Barker.) 


CUTANEOUS   SENSATIONS  169 

tive  to  light  touch  and  a  few  warm  spots  made  their  appear- 
ance. One  hundred  and  ninety  days  after  the  operation  all 
of  the  sense  qualities  had  returned  over  approximately  the 
entire  area.  But  each  of  the  sensations  was  hmited  in  some 
way  as  compared  with  the  normal.  Temperatures  below 
37°  C.  and  above  27°  C.  could  not  be  felt  at  all.  Pain  sensa- 
tions could  be  felt  only  from  unusually  intense  excitations, 
and  then  were  exceedingly  disagreeable  and  diffuse,  and 
were  generally  referred  to  some  point  at  a  distance  from  the 
one  stimulated.  Touch  could  be  felt  only  on  the  hairs,  — 
when  an  area  was  shaved,  no  touch  was  felt.  The  sensibility 
producing  this  condition  the  investigators  call  protopathic. 

Curiously  enough  one  small  triangle  in  the  affected  region 
was  discovered  in  which  all  the  quahties  were  present  that 
were  lacking  from  the  rest.  Temperatures  between  27° 
and  37°  C.  could  be  noticed,  but  none  of  the  extremes.  No 
pain  was  felt;  pricks  gave  mere  sensations  of  contact  and 
were  always  correctly  localized.  Perhaps  most  remarkable 
of  all,  light  contact  with  cotton  w^ool  was  appreciated  on 
this  small  triangle  from  the  beginning  and  was  correctly 
localized  whether  hairs  were  or  were  not  stimulated.  This 
more  highly  developed  and  more  accurate  sensibility  was 
known  as  the  epicritic.  After  the  lapse  of  a  year,  the  epi- 
critic  sense  returned  to  the  entire  area.  The  protopathic 
sensibihty  had  reappeared  in  the  small  triangle  with  epi- 
critic sensitivity  only,  one  hundred  ninety-eight  days  after 
the  operation.  This  experiment  indicates  that  three  sets 
of  sensory  nerves  supply  any  member.  One  is  found  in  the 
deep  tissues,  the  two  others  in  the  skin.  Of  the  latter  one 
provides  the  coarser,  more  intense  sensations,  the  other  the 
more  delicate.  The  protopathic  is  stimulated  only  by  rela- 
tively intense  pressure  and  that  only  on  the  hairs;  very 
intense  stimuli  also  give  pain.     It  also  is  affected  by  the 


I70        FUNDAMENTALS   OF  PSYCHOLOGY 

extremes  of  temperature  alone.  The  epicritic  sense,  on  the 
other  hand,  supplies  the  gaps  left  by  this  sense;  it  appre- 
ciates moderate  temperatures  and  slight  pressures.  The 
relation  between  the  separate  spots  that  have  been  shown 
to  produce  the  specific  sensations  and  the  epicritic  and 
protopathic  sensibilities  has  not  been  completely  worked 
out.  It  seems  difficult  at  first  sight  to  harmonize  the  two 
sets  of  results,  and  another  series  of  observations  on  a  sub- 
ject with  a  regenerating  nerve  which  shall  include  mapping 
of  the  spots  at  different  stages  is  desirable  to  complete  our 
knowledge,  and  to  determine  how  far  the  two  can  be  made 
to  agree.  1  Later  workers,  Trotter  and  Davies,^  and  Boring,^ 
have  not  confirmed  these  results  altogether.  They  found  a 
gradual  return  of  each  sense,  —  pain,  pressure,  and  cold 
returning  together,  and  warmth  considerably  later. 

Sensations  of  Taste 

Gustatory  Sensations.  —  While  tactual  sensations  have 
been  found  much  more  numerous  than  was  thought  as 
knowledge  about  them  increases,  sensations  of  taste  have 
been  diminished  in  number  quite  as  definitely  and  markedly. 
The  popular  mind  to-day  and  the  scientific  opinion  of  one 
hundred  years  ago  assumes  that  there  are  a  very  large 
number  of  taste  qualities.  Even  after  experiments  had 
been  made,  it  was  generally  beUeved  that  at  least  six  could 
be  distinguished.  The  older  list  included  nauseating  tastes, 
aromatic,  and  other  qualities  that  we  now  know  to  be 
derived  from  smell.     Chevreul  showed  in  1824  that  these 

1  Rivers  and  Head,  A  Human  Experiment  in  Nerve  Division,  Brain, 
xxxi,  323. 

2  Trotter  and  Davies,  Experimental  Studies  in  the  Innervation  of  the 
Skin.     Journal  of  Physiology,  Vol.  XXXVHI,  1909,  pp.  109,  134  ff- 

3  Boring,  Cutaneous  Sensation  after  Nerve  Division.  Quarterly  Journal 
of  Experimental  Physiology,  Vol.  X,  pp.  1-96. 


SENSATIONS   OF  TASTE 


171 


must  be  smell  qualities  by  his  discovery  that  they  disap- 
peared upon  closing  the  nostrils.  Until  relatively  recently 
salt,  sweet,  sour,  bitter,  metallic,  and  alkaline  were  regarded 
as  the  primary  tastes.  The  metalHc  seems  on  closer  experi- 
mentation to  be  a  compound  of  taste  with  smell  and  with 
mechanical  and  perhaps  muscular  sensations.  The  metallic 
surface  may  produce  slight  muscular  contractions  in  the 


Fig.  63.  —  Fungiform  pap; 


iLMu       (From  Huber.) 


neighborhood  of  contact  which  add  to  the  other  taste  and 
smell  sensations  to  produce  a  complex.  Alkalies  if  strong 
may  make  the  tongue  slippery  and  may  also  produce 
puckering  of  the  surface  of  the  tongue.  Von  Frey  has  shown 
by  closing  the  nostrils  while  tasting  that  alkahes  also  contain 
odors.  When  the  tongue  is  at  rest  and  the  nose  closed,  the 
only  sensation  is  a  shght  bitterness.  EHminating  all  sensa- 
tions of  smell,  which  furnish  a  large  part  of  what  is  called 
taste  in  gastronomic  relations,  and  all  tactual  and  tempera- 


172 


FUNDAMENTALS   OF  PSYCHOLOGY 


ture  sensations,  such  as  the  biting  of  spices,  etc.,  we  have 
left  only  four  true  tastes,  —  sweet,  salt,  sour,  and  bitter. 

Sense  Organs  of  Taste.  —  The  problem  of  the  organ  of 
taste,  and  its  specific  type  of  reaction,  is  similar  to  the  same 
problem  on  the  skin,  but  slightly  more  complicated.    The 


Subgemmal  Cell 


Intergemmal  Fibrils 

Fig.  64.  —  Taste  buds  and  endings  of  gustatory  nerve;  -«  shows  taste  cells  about 
a  central  supporting  cell;  b,  fibrils  around  and  between  the  taste  buds.  (From 
Barker.) 

sense  endings  of  taste  are  found  primarily  upon  the  tongue, 
but  also  in  some  numbers  upon  the  soft  palate,  upon  the 
cords  of  the  larynx,  the  epiglottis,  and  in  children  on 
the  inner  lining  of  the  cheek.  On  the  tongue  the  end-organs 
are  the  papillae.  These  are  elevations  set  deep  in  the  mu- 
cosa. The  sense  ends  are  on  the  sides  of  the  resulting  folds. 
The  most  striking  are  the  circumvallate  papillae,  from  seven 


SENSATIONS  OF  TASTE 


^73 


to  twelve  circular  depressions,  much  like  the  moat  of  a 
walled  town,  arranged  in  an  angle  upon  the  back  of  the 
tongue.  The  most  numerous  type  in  man  are  the  fungiform, 
whose  small  red  openings  may  be  seen  upon  the  tip  of  the 
tongue.  In  some  human  beings  the  foliate  papillae  are 
present  and  have  sense  organs.  They  are  very  prominent 
in  animals.  The  real  sense  ending  is  the  taste  hud  or  beaker. 
These  are  collections  of  taste  cells  and  supporting  cells 
arranged  in  the  form  of  a  bud.  The  taste  cells  have  hairs 
on  their  ends  that  extend  into  the  papillce  where  they  come 
into  contact  with  the  saliva  in  which  the  chemical  substance 
that  gives  rise  to  the  taste  has  been  dissolved.  Around 
the  taste  cells  are  nerve  fibrils  bare  of  their  medullary 
sheaths.  The  function  of  the  papillae  is  apparently  to 
catch  the  saliva  and  permit  it  to  come  into  contact  with  the 
taste  cells,  and  there  to  start  the  nervous  impulse. 

Doctrine  of  Specific  Energies  for  Taste.  —  Much  discus- 
sion has  been  devoted  to  the  cjuestion  whether  a  single 
taste  bud  in  a  papilla  can  give  rise  to  one  only  or  to  more 
than  one  sensation.  Experiments  performed  by  Oehrwall  of 
stimulating  the  papillae  separately  showed  that  more  than 
one  sensation  might  be  received  through  a  single  papilla. 
He  mapped  accurately  125  papillae  and  then  stimulated 
each  separately  with  solutions  of  sugar,  quinine,  and  tar- 
taric acid.  Of  these,  27  gave  no  response  at  all,  60  responded 
to  all  three  substances,  12  gave  acid  only,  3  sweet  only,  none 
bitter  only,  4  gave  sweet  and  bitter,  12  sweet  and  acid,  7 
acid  and  bitter.  From  this  experiment,  which  has  been 
repeated  by  several  investigators  with  approximately  the 
same  result,  it  is  evident  that  the  papillae  cannot  be  re- 
garded as  the  organs  of  different  special  sense  qualities  as 
are  the  spots  on  the  skin.  It  is  suggested  by  the  supporters 
of  the  doctrine  of  specific  energies  that  the  immediate  sense 


174        FUNDAMENTALS   OF  PSYCHOLOGY 

end  is  the  taste  bud  and  that,  as  there  are  always  many  of 
these  in  each  papilla,  it  is  possible  that  each  taste  corre- 
sponds to  a  particular  sort  of  nerve  end,  but  that  several 
different  kinds  are  found  in  each  papilla.  As  the  separate 
beakers  cannot  be  stimulated  individually,  this  assumption 
cannot  be  confirmed  directly.  Some  indirect  evidence  in 
its  favor  is  offered  by  the  fact  that  on  the  application  of 
certain  drugs  the  tastes  disappear  one  at  a  time,  presumably 
due  to  the  fact  that  the  primary  end  organs  are  affected 
with  different  ease.  Thus,  cocaine  applied  to  the  tongue 
destroys  first  the  sensation  of  bitter,  and  the  others  in  suc- 
cession, while  gymnemic  acid  first  destroys  the  sensation 
sweet.  Similarly,  the  distribution  of  the  taste  sensitivity 
on  the  tongue  tends  to  confirm  the  same  theory.  Bitter  is 
most  prominent  on  the  back  of  the  tongue,  —  in  some  indi- 
viduals is  confined  to  that  region ;  sweet  is  more  pronounced 
on  the  tip,  sour  on  the  sides,  while  salt  is  more  generally  dis- 
tributed. The  distribution  varies  from  individual  to  indi- 
vidual. In  some,  bitter  will  be  lacking  altogether  on  the 
tip,  while  in  others  it  is  present,  but  in  few  papillae.  A 
similar  statement  may  be  made  for  each  of  the  taste  quali- 
ties. As  further  evidence  that  there  are  specific  endings 
for  each  quality,  the  same  substance  will  produce  a  different 
taste  as  it  is  applied  to  one  part  of  the  tqngue  or  the  other: 
sodium  sulphate  has  a  sweet  taste  on  the  tip,  a  bitter  taste 
on  the  back  of  the  tongue,  a  difference  that  must  be  due 
to  the  organ  stimulated.  Similarly,  pressure  or  electrical 
stimulation  of  the  chorda  tympani,  one  of  the  nerves  of 
taste,  where  it  passes  through  the  middle  ear,  may  produce 
sensations  of  taste.  Still  another  bit  of  e\ddence  for  the 
independence  of  the  organs  for  the  different  tastes  is  differ- 
ence in  the  time  required  for  stimulation.  On  the  tip  of 
the  tongue  salt  requires  from  0.25-0.72  second  to  be  appre- 


SENSATIONS   OF  TASTE  175 

dated,  sweet,  0.30-0.85,  sour,  0.64-0.70,  bitter,  1-2  seconds. 
The  longer  time  for  bitter  is  especially  striking.  While  the 
doctrine  of  specific  energies  is  not  open  to  direct  test,  the 
indirect  evidence,  so  far  as  it  exists,  supports  the  hypoth- 
esis. 

Attempts  have  been  made  to  discover  some  relation  be- 
tween the  chemical  composition  of  substances  and  their 
tastes.  As  is  well  known,  acids  are  sour  so  generally  that 
the  two  words  are  popularly  synonymous  as  applied  to 
taste,  and  in  German  are  designated  by  the  same  word. 
There  are,  however,  many  exceptions  on  both  sides.  For 
the  other  qualities  the  lack  of  relation  between  the  chemical 
composition  and  taste  is  striking.  The  more  familiar  sweets 
are  carbohydrates,  but  lead  acetate,  salts  of  the  other  heavy 
metals,  and  even  some  alkahes  have  sweet  as  one  of  the 
component  tastes.  Much  the  same  statement  may  be  made 
of  the  bitter  substances.  Usually  they  have  a  complex 
molecule,  and  the  more  complex,  the  more  bitter,  but  no 
more  accurate  law  has  been  developed.  The  simple  salts 
are  usually  more  or  less  salt,  but  there  are  many  exceptions. 
In  general,  the  attempts  to  correlate  taste  and  chemical 
composition  have  led  to  no  noteworthy  results. 

Taste  Fusions  and  Taste  Contrasts.  —  The  taste  qualities 
show  some  of  the  interrelations  found  in  vision.  Tastes  mix 
with  each  other,  with  the  cutaneous  sensitivities,  and  with 
odors  to  produce  complexes  that  are  not  readily  analyzable. 
The  statements  hold  less  for  taste  alone  than  for  mixtures 
with  the  cutaneous  and  olfactory  senses.  It  seems  that 
sweet  and  sour,  sweet  and  bitter,  combine  in  foods  to  advan- 
tage. Salt  and  sweet  have  approximately  the  relation  of 
complementary  colors.  When  mixed  in  weak  solutions, 
Kiesow  found  that  they  nuUif)^  each  other.  Also  when 
applied  to  neighboring  areas  of  the  tongue,  they  reenforce 


176        FUNDAMENTALS   OF  PSYCHOLOGY 

each  other,  that  is,  show  contrast  effects.  Thus  if  one 
pour  upon  one  side  of  the  tongue  a  solution  of  sugar  too 
weak  to  be  tasted  alone,  and  upon  the  other  a  salt  solution, 
the  sweet  will  be  noticed.  Even  distilled  water  may  by 
the  same  means  be  given  a  sweet  taste.  Other  tastes, 
as  sweet  and  bitter,  applied  to  opposite  sides  of  the 
tongue,  when  intense,  may  alternate;  first  one  appears, 
then  the  other,  a  process  resembling  binocular  rivalry  of 
colors. 

The  nerves  of  taste  offer  some  complication.  According 
to  Zander,  there  are  three  nerves  of  taste  and  one  of  cuta- 
neous sensibility.  Of  the  true  taste  nerves,  the  glosso- 
pharyngeal, the  ninth,  supplies  the  back  portion  of  the 
tongue ;  the  vagus  supplies  the  taste  buds  of  the  larynx  and 
epiglottis  and  a  small  area  on  the  very  back  of  the  tongue; 
while  the  chorda  tympani  carries  the  sensations  from  the 
forward  areas.  The  chorda  tympani  enters  the  tongue  as  a 
part  of  the  lingualis,  the  other  portion  of  which  is  a  branch 
of  the  trigeminus,  and  is  the  nerve  of  cutaneous  sensibihty. 
In  its  midcourse  it  is  alone,  and  then  enters  the  brain  stem 
as  part  of  the  intermediate  nerve. 

Sensations  of  Smell 

Olfactory  Sensations.  —  The  organ  for  smell  is  situated 
in  a  narrow  cleft  at  the  very  top  of  the  nasal  cavity,  just 
under  the  olfactory  lobe  at  the  base  of  the  brain.  The 
olfactory  area  is  marked  by  a  brown  pigment  which  extends 
over  the  upper  portion  of  the  septum  and  the  roof  of  the 
olfactory  fissure.  The  olfactory  area  is  much  smaller  in 
man  than  in  animals  that  make  more  use  of  the  olfactory 
sense.  The  olfactory  fissure  is  above  the  direct  respiratory 
path  —  only  eddies  of  the  air  inspired  or  expired  reach  it. 
This  is  a  protective  measure,  as  dust  and  other  harmfuJ 


SENSATIONS   OF   SMELL 


177 


impurities  are  largely  prevented  from  affecting  the  endings. 
The  end  organ  proper  is  found  in  the  olfactory  cells,  truencrve- 
cells,  which  here  alone  reach  the  outer  surface  of  the  body 
(Fig.  65) .  These  cells  end  in  hairs  that  project  slightly  from 
the  surface.  The  axones  of  the  cells  pass  upwards  through 
numerous  openings  in  the  skull  to  make  connections  in  the 


Fig.  65.  —  Olfactory  apparatus.  D,  the  olfactory  membrane  and  endings;  B, 
glomeruli  where  end-brush  of  olfactory  neurones  connects  with  dendrite  of  the 
more  central  neurones.    (From  Barker,  after  Ramon  y  Cajal.) 


glomeruli  with  neurones  of  the  olfactory  lobe,  and  thence 
to  connect  with  the  cortical  areas  for  smell.  Between  the 
olfactory  cells  are  supporting  cells.  The  chemical  substance 
that  gives  rise  to  the  odor  is  carried  in  the  inspired  or  expired 
air  and  comes  into  direct  contact  with  the  hairs  of  the  ol- 
factory cells,  where  we  may  assume  that  the  chemical  reac- 
tion excites  the  nervous  impulse. 


178        FUNDAMENTALS   OF  PSYCHOLOGY 

Olfactory  Qualities.  —  How  many  sensations  of  smell 
there  are  is  still  a  moot  question.  The  organ  is  so  situated 
that  no  direct  experiment  may  be  made  upon  it,  and  the 
indirect  experiments  either  have  not  been  carried  far 
enough  or  are  inaccurate.  Aronsohn  long  ago  attempted  to 
determine  the  number  by  a  fatigue  method.  His  theory 
assumed  that  one  might  tire  the  organ  by  smelHng  some  one 
substance,  rosewater,  for  example,  until  that  substance 
could  no  longer  be  detected,  and  then  while  the  fatigue  per- 
sisted, test  the  odors  of  different  substances.  Any  that 
could  still  be  detected  would  belong  to  some  other  class, 
must  be  sensed  through  some  other  organ ;  those  that  could 
not  be  distinguished  would  belong  to  the  same  class.  The 
method  has  been  proved  to  be  practical,  but  the  large 
number  of  substances  to  be  tested  and  the  difficulty  in 
knowing  whether  the  organ  is  still  fatigued  for  the  standard 
odor  have  prevented  its  extensive  appHcation.  Other  evi- 
dence of  the  existence  of  separate  olfactory  organs  is  fur- 
nished by  pathology.  In  some  diseases  of  the  olfactory 
region,  appreciation  of  certain  odors  will  be  lost  while 
others  will  still  be  noticed.  But  the  observations  have  not 
been  carried  far  enough  to  give  an  accurate  classification. 

Henningi  has  recently  made  a  classification  of  odors  by 
questioning  men  who  had  special  skill  in  discriminating 
them.  His  conclusion  is  that  we  may  distinguish  six 
primary  qualities  with  a  series  between  each  that  partakes 
of  the  quaUties  of  the  two  extremes.  These  fundamental 
odors  are  the  spice  odors,  flower  odors,  fruit  odors,  resinous 
or  balsam  odors,  foul  odors,  and  burning  odors.  Instances 
of  the  first  class  are  fennel,  cloves,  sassafras  oil.  Included 
in  the  flower  or  fragrant  odors  are  heliotrope,  oil  of  jasmin, 

1  H.  Henning,  Der  Geruch.  Zeitschrift  f.  Psychologic,  vol.  73,  p.  161; 
vol.  74,  pp.  203,  305. 


SENSATIONS  OF   SMELL  179 

and  oil  of  geranium.  The  fruit  odors  include  the  fruits 
proper,  oil  of  citronella  and  ethyl  ether.  The  resinous  or 
balsam  combinations  include  turpentine,  oil  of  eucalyptus 
and  oil  of  cedar,  as  well  as  the  true  resins.  The  foul  odors 
are  typified  by  hydrogen  sulphide  and  other  sulphur  com- 
pounds in  addition  to  bad  cheese  and  similar  disagreeable 
odors  of  organic  origin.  The  burning  odors  are  typified  by 
smoke,  minus  the  burning  sensation,  pyridin,  and  tar. 

Henning  arranges  these  odors  on  a  prism  with  the  primary 
odors  at  the  corners  and  the  intermediate  ones  on  the  Unes 
joining  them.  Typical  intermediates  between  fruit  and 
foul  are  dill,  leek,  celery,  onion,  oil  of  mustard,  and  foul 
cheese;  between  the  burning  and  spicy  lies  browning  coffee; 
between  burning  and  resinous,  burning  varnish.  The  pri- 
mary odors  of  Henning  correspond  very  closely  with  many 
of  the  older  classifications.  The  principal  difference  is  that 
he  omits  a  number  included  by  the  older  men  which  are 
compounds  of  smell  with  pain  and  other  senses.  His 
results  can  be  readily  tested  and  on  the  whole  confirmed. 

These  quaHties  mix  with  the  cutaneous  sensations  from 
the  mucous  membranes  of  the  nose,  —  one  quahty  of  smoke, 
for  example,  is  the  same  from  the  eyes  as  from  the  nose,  — 
and  with  tastes.  We  usually  do  not  distinguish  the  different 
components:  if  the  complex  comes  from  food  in  the  mouth, 
we  call  the  whole  a  taste;  if  from  the  air  outside,  we  call 
the  whole  an  odor. 

Attempts  have  been  made  to  connect  the  qualities  of 
smell  with  the  chemical  composition  of  substances.  In 
general  it  may  be  said  that  most  odorous  substances  are 
found  in  the  fifth,  sixth,  and  seventh  groups  in  the  system 
of  Mendeleeff.  Haycraft  has  also  shown  that  in  many 
cases  the  intensity  of  the  smell  in  a  group  increases  fairly 
regularly  with  the  complexity  of  the  molecule.    There  are 


i8o        FUNDAMENTALS   OF   PSYCHOLOGY 


exceptions  to  these  rules  and  no  complete  formulation  may 
be  made  of  them.  It  is  probable  that  the  chemical  substance 
is  borne  on  the  inhaled  and  in  less  degree  by  the  exhaled  air 
to  the  olfactory  nerves  and  there  by  direct  chemical  action 
arouses  the  nervous  excitation. 

Mixtures  and  Compensations  of  Odors.  —  Mixtures  and 
compensations  of  smells  can  be  demonstrated.  For  these, 
as  for  making  all  quantitative  tests  of  odors,  Zwaarde- 
maaker  made  use  of  an  instrument  he  called  the  olfactom- 
eter.   In  essentials  it  consists  of  one  tube  with  a  curved 

end  to  be  inserted  in  the 
nostrils,  and  of  a  second 
tube  of  larger  size  contain- 
ing an  inner  hning  of  the 
substance  to  be  investi- 
gated which  slips  over  the 
former.  The  amount  of 
stimulation  is  measured  by 
the  area  of  the  outer  tube 
exposed  beyond  the  inner. 
If  they  are  even,  the  air 
entering  the  inner  tube  absorbs  none  of  the  substance  on 
the  outer;  and  the  more  the  outer  projects  beyond  the  inner, 
the  more  saturated  with  particles  is  the  air  that  enters  the 
nostril.  In  the  double  olfactometer  of  this  sort  a  tube  is  ap- 
plied to  each  nostril.  It  is  found  that  if  certain  substances, 
Peru  balsam  and  iodoform,  for  example,  are  applied  either  to 
the  same  or  different  nostrils  at  the  same  time,  they  cancel 
each  other  and  no  odor  is  sensed.  Other  substances  produce 
mixed  odors  that  may  or  may  not  be  analyzed  into  their 
components.  Xylol  and  turpentine  fuse  to  form  a  new  odor 
and  many  others  can  be  mentioned.  Certain  of  these  mixed 
odors  are  given  off  by  simple  substances,  as  can  be  shown 


Fig.    66.  —  Zwaardemaaker's    olfactom- 
eter.    (From  Titchener.) 


KINvESTHETIC   SENSATIONS  i8i 

by  the  fatigue  test.  Thus  if  propionic  acid  be  smelled  for 
some  time,  the  original  odor  will  lose  one  of  its  components 
and  assume  a  different  quality. 

REFERENCES 

Ladd-Woodworth  :     Principles    of    Physiological    Psychology, 

pp.  304-309- 
ZwAARDEMAAKER :  Physiologie  des  Geruchs,  1895. 
Titchener:  Textbook  of  Psychology,  pp.  1 14-128. 
Henning:  Der  Geruch,  igi6. 

Kinesthetic  Sensations 

Kinaesthetic  Sensations.  —  To  these  traditional  five 
senses  of  man,  modern  science  has  added  a  number  of  others. 
One  of  the  most  important  is  the  kinaesthetic,  the  sense  by 
which  we  appreciate  the  movements  of  our  own  members. 
The  muscle  sense  had  a  prominent  place  in  the  Enghsh 
psychology  of  the  last  century,  —  Thomas  Brown  and  the 
Mills  made  use  of  it,  —  but  the  first  experimental  work  of 
importance  on  the  subject  was  carried  on  by  Goldscheider 
in  the  late  eighties  of  the  last  century.  Goldscheider 
adduced  evidence  that  the  more  dehcate  sensitivity  to 
movement  was  in  the  joints  rather  than  in  the  muscles,  as 
had  been  earlier  supposed.  His  main  bit  of  evidence  for 
this  was  that  the  sensation  of  movement  is  markedly 
diminished  if  an  induction  current  is  passed  through  the 
joint  as  the  member  is  bent.  Evidently  there  are  three 
possible  sources  of  sensation  for  movement,  the  external 
skin,  which  must  be  wrinkled  at  the  joint  as  it  bends,  the 
muscles  and  tendons  which  are  known  to  be  well  suppUed 
with  sensory  endings,  and  the  joint.  Goldscheider  assumed 
on  the  basis  of  his  experiments  that  the  joint  surfaces  were 
the  organs  in  spite  of  the  fact  that  there  are  known  to  be 
no  sensory  nerves  ending  on  the  joint  surface,  and  that  an 


i82        FUNDAMENTALS   OF  PSYCHOLOGY 

experiment  that  he  made  himself  indicated  that  the  mem- 
brane on  the  joint,  the  synovial  membrane,  had  a  very  sKght 
sensitivity. 

By  anaesthetizing  these  various  sources  of  sensation  one 
after  another,  it  is  possible  to  determine  their  order  of 
importance  in  making  known  the  movements.  Experi- 
ments are  made  by  placing  the  member  to  be  tested,  usually 
the  forearm,  on  a  hinged  board,  with  the  joint  over  the 
hinge,  and  then  raising  the  board  until  the  movement  is 
first  noticed.  The  least  movement  of  the  arm  which  can 
be  appreciated  is  about  half  a  degree.  If  the  external  skin 
be  anaesthetized,  this  will  not  be  changed.  The  skin,  then, 
must  be  less  important  than  the  internal  sense  organs. 
Goldscheider  found  that  if  an  induction  current  be  passed 
through  the  joint,  there  must  be  a  considerable  increase  in 
the  movement  before  a  sensation  is  produced.  He  regarded 
this  as  evidence  that  the  joints  were  essentially  the  organs 
of  movement.  The  writer  repeated  the  experiments  and 
found  that  although  when  the  elbow  or  knee  joint  was 
anaesthetized  by  passing  an  induction  current  through  it 
the  sensitivity  for  movement  was  reduced,  it  was  also 
reduced  quite  as  much  when  an  induction  current  was 
passed  through  the  wrist  or  ankle  joint,  or  the  muscles 
near  them,  and  still  more  reduced  when,  passed  through 
both  at  the  same  time.i  From  this  it  seems  that  the  essen- 
tial organs  in  the  appreciation  of  movement  are  the  muscles 
and  tendons  with  the  sensory  nerve  ends  that  are  embedded 
in  them.  These  results  have  recently  been  confirmed  by 
von  Frey^  although  he  would  ascribe  an  important  part 

1  Pillsbury,  Does  the  Sensation  of  Movement  Originate  in  the  Joint? 
Amer.  Journ.  of  Psychology,  1901.     Pp.  346-353- 

2  Von  Frey,  Studien  iiber  den  Kraftsinn.    Zeitschr.  f.  Biologie,  vol.  68, 
PP-  349-350- 


THE   SENSE   OF   EQUILIBRIUM  183 

to  the  tactual  sensations.  This  hypothesis  is  strengthened 
by  the  histological  evidence  that  the  joint  surfaces  are  bare 
of  sense  organs,  and  by  the  fact  that  careful  observation 
indicates  that  the  movement  of  the  elbow  is  ordinarily 
felt  either  in  the  wrist  or  fingers.  Instead,  then,  of  regarding 
the  kinajsthetic  impressions  as  coming  primarily  from 
rubbing  of  joint  surfaces,  we  may  regard  the  excitation  of 
the  sensory  endings  in  the  muscles  and  tendons  by  the  con- 
traction of  the  muscle  or  the  stretching  of  the  tendon  as  the 
source  of  our  sensations  of  movement.  To  this  may  be 
added  as  a  subsidiary  factor  the  wrinkling  of  the  joint  cap- 
sule, which  also  contains  sensory  endings. 

These  kinassthetic  impressions  play  a  very  large  part  in 
our  mental  life.  It  is  of  course  important  to  know  where 
the  different  members  of  the  body  are  at  any  moment.  In 
addition  to  this  the  kinaesthetic  sensations  contribute  very 
largely  to  the  coloring  of  other  experiences;  they  guide 
the  different  movements  and  constitute  an  important  ele- 
ment in  the  emotions.  We  shall  have  occasion  to  make 
use  of  them  often  in  the  later  chapters. 

The  Sense  of  Equilibrium 

The  Static  Sense.  —  Closely  related  to  the  kinaesthetic 
sense  in  function  is  the  sense  of  equilibrium.  This  is  also  a 
sense  of  relatively  recent  discovery.  In  1872  Crum  Brown, 
Breuer,  and  Mach  independently  reached  the  conclusion 
that  the  portion  of  the  inner  ear  not  used  in  hearing,  the  so- 
called  vestibular  portion  of  the  ear,  is  closely  connected  with 
keeping  the  balance,  and  with  the  appreciation  of  the  move- 
ments of  the  body  as  a  whole.  The  evidence  accumulated 
since  is  altogether  convincing.  The  organs  involved  are 
the  sacculus,  the  utriculus,  and  the  semicircular  canals, 
named  in  order  from  the  vestibule.    The  sacculus  is  a  mem- 


i84        FUNDAMENTALS  OF  PSYCHOLOGY 

branous  sack  floating  in  the  lymph  contained  in  an  enlarge- 
ment of  the  bony  labyrinth.  This  opening  communicates 
with  the  vestibule,  and  the  lymph  is  continuous  with  the 
lymph  of  the  cochlea.  A  branch  of  the  vestibular  nerve 
enters  the  sacculus,  and  ends  in  hair  cells.  Among  the  hairs 
are  small  crystals  of  calcium  carbonate,  the  otoHths.  The 
utriculus  is  a  similar,  somewhat  larger  sack  connected  with 
the  sacculus  by  a  small  opening.    The  nerve  endings  are 

Recess.  lahyr. 


Utricul. 


Fig.  67.  —  The  left  membranous  labyrinth  of  the  ear  seen  from  without,  va, 
vp,  the  anterior  and  posterior  semicircular  canals;  h,  the  horizontal  canal.  The 
relation  of  the  sacculus  and  utriculus  to  the  cochlea  is  also  shown. 

similar  to  those  of  the  sacculus.  From  the  utriculus  extend 
the  semicircular  canals,  one  in  each  plane  of  space.  They 
have  two  openings  into  the  utriculus,  making  possible  a 
movement  of  the  lymph  through  the  complete  semicircle. 
Near  one  opening  of  each  canal  into  the  utriculus  are  small 
swellings,  the  ampulla?.  In  these  end  the  branches  of  the 
vestibular  nerve  that  go  to  each  canal.  The  nerves  end 
in  long  hairs  that  protrude  into  the  lymph  of  the  ampullae. 
The  different  branches  of  the  vestibular  nerve  unite  with 
each  other  and  join  the  cochlear  branch  to  constitute  the 
eighth  nerve.     In  the  brain  stem  the  two  branches  have 


THE   SENSE   OF   EQUILIBRIUM 


separate  nuclei.  The  nucleus  of  the  vestibular  branch  has 
connections  primarily  with  the  cerebellum  and  with  the 
nuclei  of  the  motor  nerves  of  the  eye. 

The  evidence  that  the  function  of  these  organs  is  primarily 
to  keep  the  bal- 
ance is  now  mani- 
fold. The  earlier 
investigators 
proved  that  sec- 
tioning a  semi- 
circular canal  in  a 
pigeon  disturbed 
its  balance  and 
the  tonus  of  its 
muscles,  and  at 
first  made  it 
stand  with  the 
head  drawn  to 
one  side.  It  was 
also  shown  that 
passing  a  strong 
electric  current 
through  the  ears 
would  produce  a 
turning  of  the 
head.  Studies  of 
patients  with  dis- 
eased vestibular  organs  showed  characteristic  loss  of  some 
one  function  according  to  the  part  affected  and  the  length 
of  time  the  disease  had  lasted.  Many  of  the  deaf  are  also 
defective  in  keeping  the  equilibrium.  If  one  registers  the 
movements  they  make  when  standing  erect  with  eyes  closed, 
it  is  found  that  they  sway  much  more  than  the  normal 


Fig.  68.  — Shows  the  arrangement  of  the  semicircu- 
lar canals  of  the  pigeon,  looking  from  behind  into  the 
opened  skull.  In  plane  .1  is  the  anterior  semicircular 
canal;  in  plane  P,  the  posterior;  and  in  plane  E,  the 
horizontal  of  Fig.  67. 


i86        FUNDAMENTALS   OF  PSYCHOLOGY 


Ampullar  hairs 


individual.  It  is  also  found  that  about  half  the  deaf  do 
not  have  the  compensating  eye  movements,  that  is,  the 
movements  of  the  eyes  that  make  the  eyes  turn  in  the 
direction  opposed  to  that  taken  by  the  head,  that  permit 
the  eyes  to  fixate  a  point  reflexly  in  spite  of  movements 

of  head  or  body.  In 
many  cases  the  ves- 
tibular portion  of 
the  ear  is  normal 
when  the  cochlea  is 
affected. 

Streeter  has 
shown  that  if  he 
destroys  the  vestib- 
ular region  in  the 
tadpole,  the  frog 
that  develops  from 
it  has  no  sense  of 
position,  is  as  hkely 
to  swim  on  its  back 
or  side  as  right  side 
up.  Kreidl  inserted 
iron   filings    in    the 

Fig.  6g.  —  The  hair  cells  and  the  hairs  that  pro-  _^,^„-„.„  „f  ^u^,  p^„^_ 

trude  from  the  ampulla;  of  the  semicircular  canals  OtOC>SlS  OI  tne  Cray 

into  the  liquid.  Movement  of  the  liquid  displaces  £sh*  whcn  they  Were 
the  hairs  and  stimulates  the  nerve  cell. 

opened  by  the  shed- 
ding of  the  shell,  in  place  of  the  particles  of  sand  that  nor- 
mally find  their  way  into  the  cavities  at  that  time.  After 
the  new  shell  was  grown  he  found  that  if  he  brought  a 
magnet  over  the  crayfish  they  would  at  once  turn  and  swim 
on  their  backs.  Evidently  the  attraction  of  gravitation  for 
the  sand  particles  had  been  replaced  by  the  magnetic 
1  Streeter,  Journal  of  Experimental  Zoology,  vol.  iii,  p.  543. 


Nerve  fibres 


THE   SENSE   OF   EQUILIBRIUM  187 

attraction  for  the  iron  filings.  These  various  lines  of  ex- 
perimental evidence,  together  with  the  probability  raised 
by  the  close  central  connection  of  the  nerve  with  the  cere- 
bellum and  with  oculomotor  centres,  are  conclusive  proof 
that  the  vestibule  contains  the  organ  for  the  static  sense, 
and  is  the  source  of  reflexes  for  many  eye  movements  and 
for  keeping  the  balance,  as  well  as  for  keeping  the  general 
tonus  of  the  muscles. 

The  Organs  of  Equilibration  and  their  Stimuli.  —  The 
mechanism  of  the  stimulation  of  the  sense  organs  may  be 
made  out  in  a  measure  from  the  experimental  data  and  the 
structure  of  the  organs.  Movements  of  the  body  as  a  whole 
probably  stimulate  the  sacculus  and  utriculus  primarily. 
As  the  body  moves  forward,  the  otoHths  are  left  behind 
for  a  moment  through  their  own  inertia  and  so  move  the 
hairs  and  stimulate  the  nerves.  This  excitation  occurs  only 
at  the  start;  soon  the  otoliths  take  on  the  motion  of  the 
body  and  no  further  excitation  occurs.  The  opposite 
stimulation  is  given  as  the  motion  ceases;  the  otoKths  con- 
tinue to  move  forward  under  their  own  inertia  for  a  time 
and  produce  the  same  effect  as  if  the  person  were  starting 
backward.  This  may  be  noticed  as  a  train  comes  to  a  stop. 
For  an  instant  one  seems  to  be  starting  backwards.  Going 
up  or  down,  as  in  an  elevator,  also  displaces  the  otoliths  and 
gives  the  corresponding  sensations.  Movements  of  rota- 
tion and  of  turning  the  head  in  the  different  planes  affect 
the  semicircular  canals.  The  hairs  in  the  ampulL-e  are 
probably  stimulated  by  the  movements  of  the  hquid  and 
these  stimulate  the  corresponding  nerves. 

It  is  a  question  whether  these  excitations  give  rise  to  a 
sensation  of  their  own  or  whether  they  merely  excite  reflexes 
and  these  reflexes  are  appreciated.  Violent  excitations 
produce  sensations  of  giddiness  and  finally  nausea  and  vom- 


i88        FUNDAMENTALS   OF  PSYCHOLOGY 

iting,  as  in  seasickness.  Slighter  excitations  only  call  out 
movements  of  the  eyes  and  the  movements  required  to  keep 
the  balance.  The  same  sensations  of  giddiness  and  even 
nausea  may  be  produced  by  rapid  irregular  movements  of 
the  eyes  without  movements  of  the  body.  All  of  this  speaks 
for  the  view  that  the  sensation  of  giddiness  is  not  a  true 
sensation  of  the  vestibular  nerve,  but  rather  a  sensation 
from  the  ahmentary  canal,  due  to  reflexes  excited  by  the 
organs  of  equilibrium.  On  this  theory  the  vestibular  nerve 
excites  no  peculiar  sensation,  but  serves  to  adjust  the  dif- 
ferent muscles  of  the  body,  including  primarily  the  eye 
muscles,  to  the  various  movements  of  the  body.  The  sensa- 
tions arise  from  the  reflexes  when  they  become  intense.  It 
should  be  noted  that  visual  sensations,  kin  aesthetic  sensa- 
tions, and  sensations  due  to  displacement  of  the  large  vis- 
ceral organs  also  aid  in  keeping  the  balance  and  in  appre- 
ciating the  movements  of  the  body.  The  deaf  who  have 
lost  the  sensitivity  of  the  vestibule  can,  by  means  of  these 
other  organs,  still  retain  the  balance,  though  less  accurately. 

Organic  Sensations 

Hunger    and    Thirst,    General    Sensibility.  —  Of    the 

sensations  from  the  inner  organs,  hunger  and  thirst  prob- 
ably bulk  largest  in  the  daily  hfe  of  man.  Hunger  has  been 
recently  investigated  by  Carlson  and  by  Cannon.  ^  They 
find  in  man  and  dogs  that  it  is  a  comparatively  transient 
accompaniment  of  the  deprivation  of  food.  During  a 
period  from  three  to  five  days  after  food  is  stopped,  the 
sensations  become  continually  weaker  and  gradually  prac- 
tically disappear.  They  are,  however,  rearoused  by  sight 
of  food  or  by  anything  that  suggests  food.  The  sensations 
were  found  to  be  due  to  contractions  of  the  wafls  of  the 

1  Cannon,  The  Physiological  Processes  in  Pain,  Hunger,  Fear,  and  Rage. 


ORGANIC   SENSATIONS  189 

stomach.  Records  of  these  contractions  were  taken  by- 
swallowing  a  rubber  sack  or  balloon  with  tube  attached 
which  could  be  inflated  to  fill  the  stomach,  and  then  regis- 
tering, upon  a  revolving  drum,  the  compressions  of  the  air 
in  the  balloon.  These  contractions  are  particularly  vigorous 
when  hunger  is  keenest,  and  in  general  run  parallel  to  the 
sensations.  Thirst  has  its  seat  in  the  back  of  the  throat. 
It  is  apparently  due  to  the  drying  of  the  membrane  there. 
It  may  be  relieved  by  laving  the  back  of  the  mouth  with 
citric  acid  or  by  taking  liquid  into  the  system,  either 
through  the  mouth,  through  an  artificial  opening  into  the 
stomach,  or  directly  into  the  circulation.  Each  of  these 
processes  leads  to  the  moistening  of  the  membrane  in 
question.  In  addition  to  the  qualities  of  sensation  discussed, 
there  are  a  vast  number  of  other  sensations  which  fuse  in 
the  general  complex  of  organic  sensibility.  It  is  useless  to 
speculate  upon  their  quahty  or  their  number.  With  the 
advance  of  science  others  will  undoubtedly  be  separated 
from  the  mass  and  be  recognized  as  separate  senses;  some 
already  have  names  ascribed  to  them  in  popular  speech. 
Of  these,  the  more  external,  of  tickling,  pins  and  needles, 
itching,  have  been  explained  in  different  ways;  pins  and 
needles  by  changes  in  circulation ;  tickhng  by  contractions 
in  the  skin  muscles,  survivals  of  the  fully  developed  skin 
muscles  in  animals,  or,  by  certain  authors,  as  due  to  stimula- 
tion of  tickle  spots,  a  fifth  form  of  sensory  spot  in  the  skin. 
No  one  of  the  explanations  can  be  regarded  as  more  than 
hypothetical.  The  internal  sensations  are  even  less  known 
and  few  if  any  distinctive  names  can  be  given.  Such  names 
as  are  given  refer  to  particular  complexes,  such  as  those 
present  in  the  different  emotions,  rather  than  to  specific 
sensations.  Some  of  these  inner  sensations  are  of  the  same 
quality  as  the  cutaneous  sensations,  and  are  always  fused 


I  go        FUNDAMENTALS   OF  PSYCHOLOGY 

with  sensations  from  the  contraction  of  various  muscles. 
They  are  most  frequently  fused  into  the  vague  feelings  of 
well-being  or  ill-being,  and  are  attended  to  only  as  signs  of 
health  or  of  general  bodily  state. 

The  Doctrine  of  Specific  Energies 

The  Doctrine  of  Specific  Energies.  —  A  final  problem  is 
the  bearing  of  the  results  so  far  cUscussed  upon  the  doctrine 
of  specific  energies.  We  have  found  that  law  convenient 
as  an  introduction  to  the  study  of  sensation,  and  have  used 
it  as  a  guide  throughout.  But  it  is  now  time  to  determine 
how  accurately  our  hypothesis  harmonizes  with  the  facts. 
The  doctrine  for  convenience  may  be  divided  into  different 
parts.  I .  A  nerve  end  when  stimulated  at  all  always  gives 
rise  to  its  own  pecuHar  sensation.  2.  There  are  as  many 
nerve  ends  as  there  are  specifically  different  sensations. 
3.  The  quahty  of  the  sensation  depends  upon  the  char- 
acter of  the  end  organ  rather  than  upon  the  nature  of  the 
stimulus. 

If  we  examine  these  phases  of  the  doctrine  one  by  one,  we 
find  that  the  first  holds  so  far  as  it  is  possible  to  test  it  at  all 
accurately.  It  apphes  to  the  retina,  to  the  end  organs  on 
the  skin  and  on  the  tongue,  less  certainly  to  the  olfactory 
organ.  In  discussing  the  problem  we  distinguish  adequate 
from  inadequate  stimuli.  An  adequate  stimulus  is  one  that 
excites  the  organ  in  greatest  perfection.  Light  is  an  ade- 
quate stimulus  for  the  eye,  sound  waves  for  the  ear,  etc. 
Adequate  stimuh  give  the  full  number  of  sense  quahties  of 
which  the  organ  is  capable.  Other  stimuli  are  inadequate. 
The  electric  current  is  an  inadequate  stimulus  for  all  senses, 
pressure  an  inadequate  stimulus  for  the  eye,  etc.  Each 
of  the  sense  organs  mentioned  may  be  excited  by  one  or 
more  inadequate  stimuh,  and  when  excited  responds  with 


THE  DOCTRINE  OF  SPECIFIC  ENERGIES    191 

a  sensation  of  the  quality  peculiar  to  that  sense.  The  num- 
ber of  stimuH  that  will  excite  the  organ  and  the  intensity 
of  stimulation  required  vary  from  organ  to  organ  and  for 
the  different  sense  quahties  within  the  same  organ.  The 
sensation  that  arises  when  the  organ  is  stimulated  also 
shows  various  degrees  of  approximation  to  those  excited 
by  the  adequate  stimulus.  On  the  skin,  most  of  the  organs 
may  be  excited  by  several  stimuh  and  give  approximately 
the  same  quahty  as  that  produced  by  the  adequate  stimu- 
lation. The  olfactory  endings  are  excited  with  difficulty 
and  then,  so  far  as  is  known,  only  by  electrical  stimuh,  and 
the  resulting  quahty  is  very  uncertain.  The  location  of 
the  organ  may  account  in  part  for  the  uncertainty  of  the 
result.  The  retina  has  an  intermediate  position  in  both 
respects.  Mechanical  and  electrical  stimuh  at  least  will 
affect  it,  and  they  produce  several  sensory  responses,  but 
not  the  variety  or  delicacy  of  effect  produced  by  the  hght 
waves.  While  the  law  will  not  hold  with  the  completeness 
that  a  firm  behever  might  wish,  still  it  can  be  said  in  gen- 
eral that  sense  organs  may  be  affected  by  various  stimuli, 
and  when  they  respond,  if  they  respond  at  all,  the  quahty 
is  that  ordinarily  given  by  that  organ  rather  than  the 
quahty  produced  by  the  stimulus  in  the  organ  for  which 
it  is  the  adequate  stimulus. 

The  second  law  is  less  definitely  demonstrable.  Except 
on  the  skin,  one  cannot  prove  that  each  sense  quahty  has 
a  separate  nerve  end.  From  what  we  know  of  the  eye, 
the  cones  probably  have  more  than  one  sense  quahty,  and 
while  one  might  assume  that  there  are  different  chemical 
substances  in  each  cone,  it  is  hardly  likely  that  there  are 
different  nerve  ends.  A  case  might  be  made  out  for  separate 
taste  buds  for  each  quahty;  there  is  slight  evidence  for 
separate  organs  for  each  odor.    In  hearing,  the  Helmholtz 


192        FUNDAMENTALS  OF  PSYCHOLOGY 

theory  depends  for  its  truth  upon  the  law  rather  than  sub- 
stantiates it.  Strictly,  then,  the  statement  that  there  are 
as  many  quaHties  as  there  are  sense  organs  and  no  more 
holds  only  for  certain  senses,  and  is  to  be  regarded  rather 
as  a  convenient  guide  to  the  discussion  of  sensation  than  as 
a  fully  substantiated  fact. 

The  third  principle,  that  the  quality  of  sensation  depends 
upon  the  sense  organ  excited  rather  than  upon  the  stimulus, 
holds  approximately.  Adequate  stimuli  excite  the  organ 
at  a  shghter  intensity  and  give  a  richer  quality  in  most  of 
the  sense  organs.  Nevertheless  if  one  were  to  decide  be- 
tween the  receiving  organ  or  the  external  stimulus  as  the 
determinant  of  the  sensory  quaHty,  the  receiving  organ 
must  be  given  the  more  important  part. 

There  is  also  a  question  whether,  granted  that  the  sensa- 
tions depend  upon  the  specific  characteristics  of  the  nervous 
system,  the  determinants  of  the  quahty  are  to  be  found  in 
the  sense  organ  or  more  centrally  in  the  nerves  or  their 
central  connections.  The  evidence  is  conflicting  from 
sense  to  sense.  According  to  NageP  there  is  no  good  evi- 
dence that  colors  can  be  excited  except  from  the  retina. 
Cutting  the  optic  nerve  or  turning  the  eyes  sharply  to  one 
side  or  the  other  gives  rise  to  sensations  of  light,  but  he 
thinks  both  probably  due  to  the  accompanying  pull  upon 
the  retina.  Sensations  of  taste  are  with  difficulty  or  not 
at  all  excited  by  inadequate  stimuK  upon  the  tongue,  while 
mechanical  stimuli  upon  the  chorda  tympani  where  it 
passes  through  the  middle  ear  arouse  them  certainly  and  at 
comparatively  slight  intensities.  In  the  skin  it  is  apparently 
the  end  organ  that  gives  the  pecuUar  quality.  Pressure 
upon  the  ulnar  ner\'e  gives  sensations  but  not  of  the  distinct 
qualities  that  may  be  aroused  from  the  skin.    One  cannot 

1  Nagel,  Handbuch  der  Physiologic,  Vol.  Ill,  pp.  1-15. 


WEBER'S  LAW  193 

decide  definitely  between  sense  organ  and  the  more  central 
regions.  Of  the  central  nervous  organs,  it  seems  that  the 
nerves  themselves  are  relatively  indifferent.  They  conduct 
in  either  direction,  and  sensory  nerves  may  be  made  to  carry 
motor  impulses  by  giving  them  connections  with  motor 
structures.  Whether  the  cortical  centres  have  a  specific 
function  is  still  an  open  question.  It  has  been  assumed 
by  many  authorities  that  the  qualities  of  sensation  depend 
upon  the  parts  of  the  cortex  excited.  No  actual  evidence 
for  it  has  been  collected  and  it  seems  improbable  that  it 
could  be  obtained.  In  general,  it  may  be  said  that  the  doc- 
trine of  specific  energies  of  sensory  ends  lacks  much  of  com- 
plete demonstration,  but  that  what  data  we  have  tend  to 
support  rather  than  to  refute  it.  On  disputed  points  evi- 
dence is  wanting  rather  than  opposed. 

Studies  in  Sensation  Intensities.  —  Weber's  Law 

Sensation  intensities  offer  an  entirely  different  problem 
from  qualities.  QuaHties,  as  we  have  seen,  are  ordinarily 
named,  may  be  referred  in  some  cases  to  sense  organs,  offer 
points  of  discrimination  that  may  be  recalled  in  memory,  — 
in  general  they  stand  out  for  themselves.  Intensities,  on 
the  contrary,  have  none  of  these  characteristics.  We  think 
of  a  sound  as  very  faint,  moderately  or  very  loud,  but  that 
is  all.  Intensities  have  no  real  designations,  and  cannot  be 
remembered  at  all  accurately.  It  is  perhaps  not  one-tenth 
as  bright  in  this  room  to-day  as  it  was  when  last  the  sun 
shone,  but  you  do  not  appreciate  the  difference  accurately. 
You  think  of  this  as  a  moderately  dark  day,  but  have  Httle 
idea  how  much  darker  than  yesterday.  The  same  holds  of 
weights.  Most  persons  have  great  difficulty  in  deciding 
whether  a  package  of  an  unknown  substance  weighs  one 
pound  or   two,   and    would    be    altogether   at  a  loss   to 


194        FUNDAMENTALS   OF  PSYCHOLOGY 

decide  whether  more  energy  was  exerted  on  the  ear  by  a 
telephone  held  close  to  it  or  by  a  steam  whistle  at  a 
distance. 

Measurements  of  Sensation.  —  It  has  long  been  a  prob- 
lem among  psychologists  as  to  how  intensities  may  be 
treated.  The  modern  discussion  of  the  matter  may  be  said 
to  date  back  to  Fechner,  who  thought  it  would  be  possible 
to  obtain  a  unit  for  the  measurement  of  sensation  intensities 
analogous  to  those  employed  in  physical  measurements. 
His  assumption  was  that  the  barely  distinguishable  sensa- 
tion difference,  the  difference  limen  as  he  called  it,  might  be 
made  a  unit  and  any  given  sensation  might  be  measured  in 
terms  of  the  number  of  such  units  it  contained.  This  as- 
sumed that  the  only  judgments  that  may  be  passed  on 
intensities  are  that  the  sensation  is  or  is  not  present, 
or  that  it  is  greater  or  less  than  another.  The  amount 
of  sensation  intensity  that  may  be  just  noticed,  the  limen, 
was  chosen  by  Fechner  as  the  zero  point  in  his  scale.  If 
one  should  start  with  the  faintest  sensation  that  comes 
to  consciousness,  and  determine  the  addition  that  can  just 
be  noticed,  the  liminal  sensation  might  be  called  sensa- 
tion number  one;  the  just  noticeably  different  sensation, 
sensation  number  two;  and  if  one  should  continue  the 
process,  it  would  be  possible  to  determine  the  entire 
number  of  differences  that  could  be  noted  in  the  series 
of  sensations,  and  thus  the  entire  number  of  sensation 
intensities  in  any  sense  department.  It  would  also  be 
possible  to  measure  any  sensation  by  the  number  of  these 
unit  intensities  that  were  contained  in  it.  Unfortunately, 
however,  the  facts  are  by  no  means  so  simple  as  this  theory 
would  assume.  The  least  intensity  that  can  be  noticed  is 
not  fixed  even  for  the  same  individual,  and  the  number  of 
units  that  can  be  noticed  is  also  variable.    In  consequence, 


WEBER'S   LAW  195 

this  scheme,  attractive  as  it  is  in  theory,  has  never  been 
and  apparently  cannot  be  applied  in  practice. 

Weber's  Law.  —  Out  of  the  very  large  number  of  experi- 
ments devoted  to  these  measurements,  a  law  has  developed 
that  is  of  great  interest.  Very  briefly,  it  has  been  found 
that  the  size  of  the  just  noticeable  increment  is  not  the  same 
for  all  intensities,  but  increases  with  the  absolute  intensity 
of  the  stimulus,  and  bears  a  constant  ratio  to  that  intensity. 
Thus  Weber  found  that  if  a  weight  of  32  ounces  were  lifted, 
it  could  be  noted  that  30  ounces  was  just  less,  while  if  32 
drachms  were  lifted,  30  drachms  could  just  be  noticed  to  be 
different.  A  difference  of  a  fifteenth  of  the  total  weight 
could  be  noted  whether  the  units  were  ounces  or  drachms. 
These  relatively  crude  experiments  have  been  repeated 
and  improved  upon  by  a  number  of  later  workers,  Fechner 
in  particular,  and  show  the  same  general  law.  The  fraction 
of  the  total  intensity  that  may  be  just  noticed  varies  from 
one  sense  to  another,  but  holds  with  fair  accuracy  for  the 
same  sense.  The  values  range  from  approximately  y^o  for 
sight  to  one-third  or  one-fourth  for  smell.  In  giving  these 
values,  it  should  not  be  assumed  that  the  just  noticeable 
difference  is  absolutely  constant  even  under  constant 
objective  conditions  or  under  conditions  that  are  as  nearly 
constant  as  can  be  obtained.  Differences  in  the  order  in 
which  stimuli  to  be  compared  are  given,  in  the  degrees  of 
attention  at  different  times,  and  in  the  way  in  which  the 
suggestions  that  may  be  given  unintentionally  may  work, 
all  have  an  influence  upon  the  determination  of  the  dif- 
ference limen.  In  consequence,  it  is  not  often  that  two 
consecutive  experiments  will  give  the  same  result.  All 
values  given  are  averages  obtained  with  the  same  indi- 
vidual, and  where  several  values  are  given  it  is  assumed  that 
the  two  are  extremes  for  the  subjects  used.    Occasionally  the 


196        FUNDAMENTALS   OF  PSYCHOLOGY 

values  obtained  from  different  observers  will  be  averaged, 
but  this  is  not  at  present  regarded  as  advisable.  The  results 
are  not  to  be  regarded,  as  in  physics,  as  constant  values  that 
are  obscured  by  the  varying  conditions  of  observations,  but 
as  fundamental  differences  due  to  the  differences  between 
individuals. 

Departures  from  Weber's  Law.  —  It  is  also  true  that  the 
fraction  varies  for  the  different  absolute  intensities.  It  is 
always  greater  for  the  extreme  intensities,  and  even  within 
what  may  be  called  the  mean  values,  there  is  often  a  gradual 
change.  The  first  fact  can  be  seen  in  many  of  the  simple 
phenomena  of  daily  Hfe.  The  increase  in  the  least  noticeable 
difference  at  maximum  intensities  is  illustrated  in  the  diffi- 
culty in  reading  when  the  sun  is  shining  on  the  page,  as 
the  difficulty  in  reading  in  faint  light  illustrates  the  increase 
of  the  relative  difference  at  the  lower  range  of  intensities. 
The  relative  amount  of  light  reflected  and  absorbed  is  the 
same  at  all  intensities,  but  the  relative  difference  that  may 
be  discriminated  is  much  greater  at  the  extremes  of  absolute 
intensities.  Were  relative  differences  discernible  with  equal 
ease  at  all  intensities,  one  could  read  as  readily  by  moon- 
light as  by  electric  light,  and  in  the  glare  of  the  sun  as  well 
as  in  the  shade. 

The  values  that  have  been  obtained  in  the  more  important 
senses  range  for  vision  from  ws  to  tIs  for  different  observers 
and  different  intensities.  For  hearing,  Wien,  using  tele- 
phone tones,  obtained  a  fraction  of  i  to  i;  for  pressures, 
values  have  been  obtained  from  to  to  3V,  depending  upon 
the  part  of  the  body  stimulated.  Lifted  weights  give  a  much 
smaller  value  than  passive  pressure,  from  2V  to  t^,  according 
to  Biedermann  and  Lowitt,  according  to  Weber  iV •  Taste, 
smell,  and  temperature  all  offer  difficulties  in  the  technique, 
and  the  results  are  correspondingly  unsatisfactory.     The 


WEBER'S  LAW  197 

values  of  the  fraction  for  these  senses  are  generally  given 
as  ranging  from  i  to  i. 

The  Limen  for  Sensation.  —  The  results  of  the  investiga- 
tions of  the  least  intensities  that  can  be  perceived,  the  abso- 
lute sensation  limen,  have  also  been  determined  for  certain 
senses  with  a  satisfactory  degree  of  accuracy.  For  sight 
and  sound  the  values  can  be  given  in  terms  of  absolute  units. 
Langley  found  that  the  eye  was  sensitive  to  light  waves 
that  exerted  an  energy  of  .00000003  ^^g.  Wien  found  that 
the  ear  would  respond  to  still  smaller  values:  from  .000004 
erg  for  tones  of  50  V  D  per  second  to  .0000000000000005 
erg  for  tones  of  3200  V  D  per  second.  For  pressure,  the 
most  reHable  results  are  those  given  by  von  Frey.^  He 
found  the  energy  required  to  excite  a  hair  to  be  about  3V  of 
an  erg,  and  to  excite  a  pressure  spot  on  the  skin  about  i 
of  an  erg.  Values  obtained  for  other  senses  have  relatively 
Little  meaning,  as  they  cannot  be  statedin  terms  of  energy. 

Theories  of  Weber's  Law.  —  It  can  be  asserted,  then, 
that  within  hmits  Weber's  law  holds.  Differences  in  two 
stimuH  are  noticed  more  easily  when  the  absolute  stimuli 
are  low  than  when  they  are  high,  and  the  addition  that 
can  just  be  appreciated  is  a  constant  fraction  of  the  stimulus 
already  present.  The  explanations  of  tliis  law  fall  into  three 
groups.  Wundt  holds  that  the  law  has  a  purely  mental 
basis,  that  it  is  but  one  expression  of  the  general  law  of 
relativity;  all  things  are  estimated  in  terms  of  other  things 
that  may  be  in  consciousness  at  the  moment.  This  is 
merely  a  restatement  of  the  law  rather  than  an  explanation. 
Fechner  regarded  the  law  as  an  expression  of  the  general 
relation  between  body  and  mind.  These  were  two  phases 
of  a  single  substance  for  him,  Hke  the  inside  and  outside 
of  a  circle,  and  in  some  way  not  made  clear,  stimuH  that 

*  Von  Frey,  Zeitschrift  f.  Biologic,  vol.  Ixx,  p.  ^33- 


198        FUNDAMENTALS   OF  PSYCHOLOGY 

increase  in  a  geometrical  ratio  produce  an  increase  in  mind 
in  an  arithmetical  ratio.  A  third  theory,  developed  in  large 
degree  by  G.  E.  MuUer,  explains  the  law  as  due  to  the  loss 
in  intensity  that  a  nerve  impulse  undergoes  in  passing 
through  the  nervous  system  itself.  That  such  a  loss  does 
take  place  is  suggested  by  the  experiments  of  Waller  with 
the  optic  nerve  and  retina  of  a  frog.  The  current  of  action 
of  the  nerve  excited  by  different  intensities  of  Hght  upon 
the  retina  was  measured  and  it  was  found  that  the  current 
of  action  was  related  to  the  intensities  of  stimulus  in  the 
arithmetical-geometrical  ratio.  Miiller  asserts  that  the 
more  intense  the  stimulus,  the  more  opposition  is  offered 
to  its  passage  through  the  nervous  system,  and  in  conse- 
quence the  more  is  lost,  —  a  smaller  proportion  reaches  the 
brain.  If  the  amount  lost  —  and  so  the  amount  retained 
—  is  proportional  to  the  absolute  intensity  of  the  stimulus, 
the  demands  of  Weber's  law  are  satisfied.  Ebbinghaus  has 
suggested  that  this  increased  loss  can  be  explained  on  the 
assumption  that  there  are  in  the  nerve  chemical  substances 
which  decompose  with  different  degrees  of  difficulty.  The 
less  intense  stimuli  use  up  the  more  readily  decomposable 
elements,  and  hence  produce  a  relatively  great  effect  on 
consciousness,  and  the  stimulus  must  exhaust  an  increas- 
ingly greater  amount  of  energy  in  affecting  the  components 
next  higher  in  the  degree  of  difficulty  of  decomposition. 
Whatever  the  detailed  explanations,  the  facts  available 
indicate  that  the  law  is  due  to  the  increasing  resistance 
offered  in  the  nervous  system  to  the  transmission  of  the 
more  intense  nerve  impulses,  that  the  explanation  is  physi- 
ological .rather  than  psychophysical  or  purely  psycho- 
logical. ^ 

1  Titchener,  Manual  of  Psychology,  Instructor's  Manual.   Quantitative. 


CHAPTER  VI 

THE    ORIGINAL    NATURE    OF    MAN,    AND    THE 
MEANS  OF  MODIFYING  BEHAVIOR 

We  have  now  summarized  the  more  important  facts  which 
are  prehminary  to  any  study  either  of  the  behavior  of  man 
or  of  his  consciousness.  The  nervous  system  makes  possible 
all  activity;  and  the  sense  organs  through  their  stimulations 
supply  the  incentives  for  all  movement  and  also  provide  the 
materials  that  are  manipulated  in  the  acquisition  of  knowl- 
edge of  any  type.  The  nervous  system  has  within  it  at 
birth  the  connections  that  make  possible  the  instincts  and 
reflexes;  potentially  it  has  the  capacity  for  forming  the 
connections  upon  which  depend  all  acquisition  of  habits, 
and  the  form  of  learning  which  we  popularly  call 
memory. 

Nature  and  Nurture.  —  When  we  turn  from  the  discus- 
sion of  the  physiological  structures,  which  must  be  under- 
stood prior  to  any  study  of  psychology,  to  the  actual  inves- 
tigation and  explanation  of  man's  activities  and  Hfe,  there 
are  two  opposing  tendencies  which  must  be  taken  into  con- 
sideration in  the  explanation  of  every  phase  of  conduct 
and  of  thought.  These  are  known  roughly  as  instinct  and 
hahit,  or  even  more  generally  as  nature  and  nurture. 
Briefly  these  terms  mean  that  the  man  is  determined  in  his 
responses  and  in  his  thinking  by  characteristics  inherited 
from  his  immediate  ancestors  and  from  the  race  as  a  whole, 
and  by  certain  other  characteristics  developed  by  the 
environment  in  which  he  lives.  The  one  is  present  at  birth 
199 


200        FUNDAMENTALS   OF  PSYCHOLOGY 

or  is  the  immediate  outcome  of  the  growth  of  his  nervous 
system;  the  other  is  a  direct  product  of  Uving  and  learning, 
of  his  adaptation  to  the  world  about  him.  These  two  op- 
posing groups  of  forces  are  frequently  difficult  to  distinguish, 
and  they  almost  always  interact  in  determining  both  the 
general  capacity  of  the  individual  and  the  nature  of  his 
specific  responses  to  any  given  situation.  Still  they  must 
be  regarded  as  distinct  in  our  discussion. 

The  native  endowment  of  the  individual  includes  both 
the  capacities  distinguishable  at  birth  and  those  which  are 
to  develop  later.  If  one  look  at  a  new-born  infant  and  study 
its  responses,  one  sees  in  it  relatively  Httle  of  the  powers 
that  it  is  to  develop.  An  occasional  cry,  a  few  reaching 
movements,  and  the  reactions  of  nursing,  give  about  the 
only  evidence  of  inteUigence.  There  is  no  way  of  deter- 
mining at  this  stage  what  the  future  capacity  is  to  be.  An 
observer  could  not  tell  a  future  Darwin  from  a  possible 
criminal  or  imbecile  by  any  of  the  tests  known  to  science, 
if  he  did  not  have  a  knowledge  of  the  heredity  of  the  child. 
Even  an  acquaintance  with  the  heredity  gives  only  the 
possibihty,  not  complete  assurance,  of  the  career  that  is  to 
be.  Nevertheless  we  must  beheve  that  a  large  part  of  the 
accomplishment  of  the  child  is  already  determined.  Train- 
ing and  the  effect  of  environment  will  serve  to  bring  out 
what  is  already  there,  but  in  the  absence  of  certain  as  yet 
unknown  characteristics  of  the  nervous  system,  no  amount 
of  training  or  stimulation  would  suffice  to  produce  great 
abihty. 

Two  fundamental  forms  of  native  endowment  may  be 
distinguished.  One  determines  the  specific  responses  of 
all  individuals  of  a  species  to  given  situations;  these  are 
the  reflexes  and  instincts.  The  other  determines  the  more 
general  capacity  for  learning  and  response,  the  intelligence, 


INTELLIGENCE,  TEMPERAMENT,  WILL    201 

temperament,  and  disposition  of  the  individual.  The 
reflexes  and  instincts  we  regard  as  the  forces  that  make  all 
individuals  respond  in  approximately  the  same  way;  the 
other  forms  of  equipment  give  rise  to  the  differences  be- 
tween individuals.  Both  are  due  to  heredity.  The  first 
group  designates  the  inherited  similarities  in  response; 
the  second,  the  inherited  differences.  Another  distinction 
is  that  the  instincts  and  reflexes  show  themselves  in  actual 
responses,  while  the  other  terms  indicate  only  capacities 
for  responses  or  for  learning,  or  the  tendencies  to  emo- 
tion. 

Intelligence,  Temperament,  Will.  —  We  distinguish  three 
ways  in  which  individuals  may  differ  in  capacity:  in  intelli- 
gence, in  temperament  —  or  the  hability  to  certain  emo- 
tions, and  in  the  volitional  characteristics  of  action  —  the 
qualities  of  the  will.  The  definition  of  these  terms  has  gone 
little  farther  in  psychology  than  in  popular  usage.  By 
intelligence  we  mean  the  ability  to  think  to  good  effect,  to 
appreciate  situations,  and  easily  find  the  solution  for  the 
difficulties  they  present,  to  appreciate  ends  and  to  be  able 
to  work  consistently  towards  those  ends.  In  practice,  in- 
telHgence  goes  very  closely  hand  in  hand  with  the  ability 
to  maintain  one's  self  in  a  given  environment,  physical  and 
social.  The  temperaments  are  not  clearly  differentiated, 
although  all  admit  that  both  for  scientific  classification  and 
for  the  treatment  of  mental  diseases,  it  is  desirable  to  push 
our  analysis  farther  and  to  secure  tests  that  shall  measure 
temperamental  differences.  The  volitional  characteristics 
are  also  important,  but  we  know  only  that  differences  in 
the  ability  or  willingness  to  work  persistently  to  a  desired 
end  influence  markedly  the  success  of  individuals  of  the 
same  intelligence. 


202        FUNDAMENTALS   OF  PSYCHOLOGY 

Intelligence  Tests 

Binet  Tests.  —  Tests  of  intelligence  have  been  developed 
in  great  number  and  several  of  them  have  been  standardized 
to  the  point  where  the  wider  differences  may  be  measured 
with  considerable  accuracy.  All  are  alike  in  requiring  the 
individual  to  be  tested  to  carry  through  a  number  of  rela- 
tively simple  mental  and  physical  operations  in  which  he 
may  be  rated  for  quickness  and  accuracy.  The  two  tests 
which  have  had  the  widest  use  and  are  in  many  ways  best 
adapted  to  the  purpose  are  the  Binet  tests  and  the  tests 
developed  for  the  examination  of  the  intelligence  of  the 
United  States  soldiers  in  the  World  War  and  consequently 
known  as  the  Army  Tests.  The  Binet  tests  were  developed 
on  the  assumption,  which  the  outcome  verified  in  general, 
that  one  might  measure  the  intelligence  of  any  one  below 
the  average  inteUigence,  by  comparing  his  accomplishment 
in  a  series  of  tests  with  the  accomplishment  of  a  child  of 
some  given  age.  It  was  assumed  that  the  child  begins  with 
approximately  zero  intelligence,  and  then  passes  through 
all  degrees  until,  if  an  average  child,  he  reaches  average 
adult  intelligence.  Binet  devised  a  group  of  tests  for  each 
age,  which  the  average  child  of  that  age  could  just  pass. 
These  were  tested  on  a  large  number  of  children  and  in 
actual  practice  arranged  in  groups  on  the  basis  of  the  results 
obtained.  The  tests  ranged  in  difficulty  from  naming  the 
parts  of  the  face  and  simple  objects,  to  defining  abstract 
words  and  stating  the  difference  between  a  king  and  a 
president,  on  to  comphcated  arithmetical  puzzles.  Much 
depends  throughout  upon  memory  for  immediately  pre- 
ceding events,  upon  the  amount  learned  from  what  is  as- 
sumed to  be  the  environment  of  the  normal  child,  and  upon 
abihty  to  appreciate  situations  and  apply  simple  remedies  in 


INTELLIGENCE  TESTS  203 

case  of  difficulty.  One  test  alone  would  have  little  signifi- 
cance, but  a  number  taken  together  give  a  fairly  accurate 
idea  of  the  capacity  of  the  individual. 

The  Mental  Age  and  Intelligence  Quotient.  —  Binet's 
most  important  contribution  to  the  methods  of  testing  was 
in  using  the  capacity  of  children  of  different  ages  as  a  stand- 
ard of  comparison.  After  one  has  discovered  which  of  the 
group  of  tests  the  individual  can  pass,  one  has  a  measure 
of  his  intelligence  in  years,  which  is  now  generally  called 
his  mental  age.  If  of  average  abiUty,  his  mental  age  and  his 
chronological  age  are  the  same;  if  he  has  developed  more 
slowly  than  the  average  child  he  will  be  retarded  by  one  or 
more  years.  The  mental  age  gives  an  immediate  indication 
of  the  intelligence  of  an  adult.  The  mental  age  scale  is 
applicable  readily  and  satisfactorily  to  children  and  to 
defective  adults.  Since  the  average  child  reaches  his 
maximum  development  at  thirteen,  it  is  obvious  that  the 
measure  cannot  be  used  for  adults  of  more  than  average 
ability.  Recently  in  revising  the  scale,  Terman  suggested 
that  one  could  state  the  intelligence  of  an  individual  irre- 
spective of  his  actual  age,  if  one  used  the  ratio  of  mental 
age  to  chronological  age  as  the  index  of  intelligence.  If 
one  divide  the  mental  age  by  the  chronological  age,  one 
obtains  what  he  calls  the  intelligence  quotient,  usually  abbre- 
viated as  the  I.  Q.  The  I.  Q.  of  the  average  individual  is 
100.  The  justification  for  using  the  ratio  of  mental  to 
chronological  age  is  that  tests  show  that  this  ratio  remains 
fairly  constant  throughout  life.  If  a  child  is  one  year 
behind  at  four,  he  will  usually  be  two  years  behind  at  eight 
and  three  years  behind  at  twelve.  His  I.  Q.  would  be  con- 
stant at  75.  If  a  child  were  one  year  ahead  at  five,  he  would 
similarly  be  two  years  ahead  at  ten  and  would  have  an 
intelUgence  quotient  of  120.    One  Hmitation  of  the  method 


204        FUNDAMENTALS   OF  PSYCHOLOGY 

is  that  only  a  young  child  can  make  a  very  high  rank.  The 
highest  age  for  which  tests  are  given  by  Terman  is  twenty. 
In  consequence,  a  child  of  sixteen  would  be  limited  to  an 
I.  Q.  of  1 25,  while  a  ten-year-old  might  make  200.  The  tests 
beyond  fourteen  have  little  relation  to  the  accomplishments 
of  actual  children,  as  few  children  reach  that  level. 

The  Distribution  of  Intelligence.  —  So  far  as  results  go, 
inteUigence  seems  to  be  distributed  in  accordance   with 


Fig.  70.  —  The  distribution  of  stature  among  French  soldiers.  The  distances 
on  the  horizontal  axis  indicate  the  height  in  centimetres,  on  the  vertical  axis,  the 
number  of  men  of  heights  between  the  figures  printed  below  the  line.  (From  Ber- 
tillon:   Instructions  signaletiques.) 

what  the  mathematician  calls  the  normal  frequency  curve. 
It  is  the  curve  that  results  if  one  plots  a  large  number  of 
measurements  of  any  kind  on  unselected  individuals. 
Figure  70  shows  the  curve  that  results  from  plotting  the 
heights  of  a  thousand  French  soldiers,  indicating  the  height 
in  centimeters  above  100  on  the  base  line  and  the  number 
of  individuals  who  are  of  the  given  stature  on  the  vertical 
distance.  The  average  in  this  case  was  164^  cm.  There 
are  just  as  many  who  are  taller  as  shorter,  and  the  greater 
the  distance  from  the  average  the  fewer  are  the  individuals 
represented.    There  are  236  between  163  and  166,  but  only 


I 


INTELLIGENCE   TESTS  205 

10  each  who  are  less  than  141  cm.  or  more  than  180  cm.  tall. 
Terman  found  that  intelligence  is  distributed  in  the  same 
way.  About  60  per  cent  fall  within  ten  points  on  either  side 
of  the  average,  and  have  an  intelHgence  quotient  between 
90  and  no.  These  are  the  average  individuals.  There  are 
about  14  per  cent  between  80  and  90,  and  between  no 
and  120;  about  5  per  cent  each  in  the  next  range  of  ten 
points  to  70  below  and  130  above;  and  i  per  cent  below  a 
quotient  of  70  and  with  130  and  above.  Those  below  70 
are  ordinarily  counted  as  feeble-minded;  that  is  they  are 
sufficiently  deficient  to  be  likely  to  become  a  charge  on  the 
community,  while  those  above  130  are  exceptional,  and 
are  ranked  by  Terman  as  geniuses  or  near  geniuses. 

The  Army  Tests.  —  In  the  Army  Tests  the  method  of 
measuring  capacity  is  to  compare  the  accomplishment  of 
the  indi\ddual  with  the  performance  of  a  large  number  of 
other  individuals  and  give  him  a  rating  relative  to  the  group. 
It  consists  of  a  series  of  questions  to  test  arithmetical  skill, 
general  information,  abihty  to  understand  and  follow  direc- 
tions and  to  comprehend  different  relations.  It  could  be 
given  in  less  than  an  hour  to  two  hundred  or  more  men  at 
once,  and  as  it  was  given  to  a  million  and  three  quarter  men, 
the  results  sufficed  to  give  an  excellent  idea  of  the  distribu- 
tion of  intelHgence  in  the  general  population.  Like  the 
Terman  test,  it  shows  that  the  distribution  of  intelligence 
follows  the  normal  frequency  curve.  The  total  possible 
score  was  212.  On  both  tests  the  intelligence  was  found 
to  be  symmetrically  distributed.  About  4  per  cent  made  a 
better  score  than  140  and  about  7  per  cent  made  a  lower 
score  than  14.  The  first  were  designated  as  an  A  group, 
the  lower  as  an  E;  similar  intermediate  grades  were  made. 
The  men  of  the  A  group  were  found  to  be  of  intelligence 
suited  for  high  command,  pro\ided  they  had  the  emotional 


2o6        FUNDAMENTALS   OF  PSYCHOLOGY 

and  volitional  characteristics.  The  lowest  group  was  dis- 
missed from  the  service,  or,  more  usually,  transferred  to  a 
service  battalion,  as  they  were  of  no  military  value.  In 
civilian  life  the  A  group  men  were  found  to  be  from  the  pro- 
fessions and  to  have  been  the  successful  men,  while  the  D 
and  E  group  men  were  from  the  ranks  of  common  labor 
and  had  had  little  success  in  that  role.  On  the  whole  it  was 
found  that  the  degree  of  intelligence  as  shown  in  the  tests 
was  closely  correlated  with  the  grade  that  had  been  reached 
in  the  educational  system.  The  E  men  had  seldom  gone 
beyond  the  third  grade,  while  many  of  the  A  men  were 
college  men.  This  does  not  mean  that  the  education  had 
necessarily  made  them  intelligent,  but  that  their  intelligence 
had  made  it  possible  for  them  to  go  as  far  as  they  did  in  the 
school  system.  The  results  of  the  tests  as  a  whole  are  im- 
portant in  showing  the  wide  differences  in  the  intelHgence 
of  the  general  population,  and  also  in  indicating  the  natural 
selective  agencies  that  roughly  adjust  the  individuals  of 
different  intelHgence  to  the  callings  that  are  best  suited  to 
their  abilities. 

The  results  of  the  tests  are  important  psychologically  in 
indicating  how  differently  we  must  treat  different  individ- 
uals in  psychological  experiments.  The  general  laws  of 
mental  action  are  the  same  for  all,  but  the  amount  that  can 
be  expected  of  individuals  will  differ  greatly.  The  results 
of  the  army  tests  and  of  the  Binet  tests  taken  together  indi- 
cate that  intelhgence  is  distributed  very  much  as  stature  is. 
There  are  a  large  number  of  average  men.  About  68  per 
cent  of  all  fell  in  the  C  grade  on  the  army  scale,  as  most 
men  would  fall  within  three  inches  of  the  average  in  height. 
The  farther  away  from  the  average  any  measurement  lies, 
the  smaller  the  number  of  individuals  who  fall  in  the  class. 
Practically,  the  results  are  of  value  in  indicating  the  limita- 


CHARACTER  TESTS  207 

tions  of  certain  individuals  for  the  higher  types  of  training 
and  even  for  life  in  society.  The  schools  have  found  the 
tests  of  value  in  sorting  out  those  who  are  incapable  of 
doing  good  work  or  of  keeping  up  with  the  grade.  The  worst 
must  be  given  a  special  kind  of  training;  and  the  better 
types,  when  put  by  themselves,  can  be  taught  by  different 
methods  and  permitted  to  learn  at  a  faster  rate.  Tests  of 
prisoners  in  civiUan  hfe,  particularly  the  juvenile  prisoners, 
have  shown  that  many  of  them  are  below  normal  mentally, 
as  are  also  many  of  the  paupers  and  others  who  have  diffi- 
culty in  maintaining  themselves.  Recognition  of  the  differ- 
ences in  intelHgence  is  necessary  to  an  understanding  of 
many  social  problems. 

Character  Tests 

Investigations  of  Character.  ^  Differences  in  emotional 
and  voUtional  characteristics  undoubtedly  exist,  but  accu- 
rate measurements  have  not  been  made  of  them.  So  far 
no  scheme  of  measurement  has  been  devised,  much  as  that 
is  needed,  particularly  by  the  speciaHst  in  nervous  diseases, 
since  emotional  disturbances  are  strikingly  frequent  in 
the  causation  of  such  troubles.  An  investigation  by  Webb 
sought  to  determine  the  differences  by  having  the  degree 
in  which  individuals  possess  certain  traits  rated  by  judges 
who  knew  them  well.  He  chose  certain  characters  that  are 
fairly  easy  to  note,  such  as  readiness  to  anger,  eagerness  for 
admiration,  bodily  activity  in  the  pursuit  of  pleasure,  per- 
sistence of  motives,  continuance  towards  a  goal  in  spite  of 
obstacles,  trustworthiness,  conscientiousness,  etc.  He  found 
that  certain  of  these  traits  correlated  closely  among  them- 
selves. They  could  be  divided  into  two  classes :  a  desirable 
group,  including  persistence  of  motives  that  lead  towards 
a  remote  goal,  quick  recovery  from  anger,  conscientiousness, 


208        FUNDAMENTALS   OF  PSYCHOLOGY 

which  were  likely  to  be  possessed  in  approximately  the  same 
degree  by  the  same  individuals;  and  an  undesirable  group, 
exhibiting  readiness  to  anger,  eagerness  for  admiration,  and 
bodily  activity  in  the  pursuit  of  pleasure.  If  a  man  stood 
high  in  one  he  was  likely  to  be  ranked  low  in  the  other  group. 
These  traits,  too,  were  likely  to  have  a  relation  to  the  pos- 
session of  intelligence.  A  man  who  possessed  the  desirable 
group  in  considerable  measure  was  also  likely  to  stand  high 
in  intelligence,  while  a  man  who  had  the  undesirable  group 
in  considerable  amount  would  be  lower  in  intelligence.  It 
is  obvious  that  both  the  emotional  and  volitional  character- 
istics would  be  important  factors  in  determining  the  success 
of  an  individual  in  tests  or  in  obtaining  grades,  but  the 
investigations  endeavored  to  distinguish  between  the  quali- 
ties. The  results  indicate  a  condition  which  is  found  fairly 
generally  in  the  study  of  individual  differences  —  that 
desirable  qualities  of  all  kinds  go  together.  There  is  no 
compensation  in  the  bestowal  of  traits.  A  man  who  stands 
well  in  one  desirable  quality  will  stand  well  in  all,  and  vice 
versa.  There  are  occasional  men  with  good  intelligence 
who  fail  because  of  lack  of  persistence  or  of  social  adapta- 
bility. Fortunately  these  are  the  exception  rather  than 
the  rule. 

Individual  Differences 

The  Coefficient  of  Correlation.  —  In  discussions  of  statis- 
tical matters  it  is  frequently  necessary  to  indicate  the  degree 
of  similarity  between  individuals  and  the  likelihood  of  the 
appearance  of  different  traits  in  conjunction.  This  relation 
can  be  stated  in  a  single  number  by  the  coefficient  of  corre- 
lation. If  we  have  two  traits  and  desire  to  determine  the 
degree  in  which  they  are  likely  to  go  together  in  individuals, 
we  can  measure  the  relation  and  state  it  by  the  coefficient 


INDIVIDUAL  DIFFERENCES  209 

of  correlation.  .  For  example,  in  order  to  determine  the  rela- 
tion between  intelligence  and  stature,  one  may  measure  the 
degree  of  connection  by  arranging  a  large  number  of  indi- 
viduals in  their  order  with  reference  to  each  of  these  charac- 
ters and  determining  the  relative  ranking  in  each.  Should 
there  be  a  complete  identity  between  the  two  traits,  the 
individual  who  ranked  first  in  one  would  be  first  in  the  other; 
the  individual  who  was  second  in  one  would  be  second  in 
the  other,  etc.  If  this  relation  held,  we  would  have  a 
coefficient  of  correlation  of  i.e.  On  the  other  hand,  were 
height  in  some  way  inimical  to  intelligence,  we  might  find 
that  the  shortest  individual  was  most  intelligent,  the  next 
shortest  ranked  second  in  intelhgence,  and  so  on.  In  the 
case  of  such  a  relation,  we  would  have  a  coefficient  of  —  i  .0. 
Such  absolute  agreement  is  never  found.  What  we  do  find 
is  that  many  of  the  men  who  stand  high  in  one,  will  stand 
high  in  the  other  also;  while  in  the  case  of  negative  corre- 
lations, many  or  most  of  the  men  who  are  above  the  average 
in  one  will  be  below  average  in  the  other.  These  are  repre- 
sented by  numbers  between  zero  and  i.o  or  between  zero 
and  minus  i.o;  the  nearer  i.o,  plus  or  minus,  the  greater 
the  degree  of  similarity  or  dissimilarity.  The  methods  of 
obtaining  the  exact  values  may  be  found  in  treatises  on 
statistical  method.  Yule's  "  Theory  of  Statistics,"  for  ex- 
ample. A  coefficient  of  correlation  seldom  is  above  .90.  One 
below  0.35  indicates  relatively  little  similarity,  unless  ob- 
tained from  a  very  large  number  of  individuals.  Such  a 
correlation  as  that  between  height  and  standing  in  mental 
tests  would  be  possibly  0.5-0.10.  It  seems  to  be  positive 
but  so  slight  as  to  indicate  nothing.  The  correlations 
between  common  sense  and  readiness  to  anger,  in  Webb's 
work,  was  -.53;  while  that  between  common  sense  and 
originahty  was  0.84. 


2IO        FUNDAMENTALS   OF  PSYCHOLOGY 

The  Causes  of  Individual  Differences.  —  When  we  raise 
the  question  of  the  origin  of  the  differences  in  inteUigence 
or  in  temperament,  we  find  that  there  are  two  possible 
answers.  On  the  one  hand  we  might  assume  that  all  was 
/^  due  to  heredity  or  that  all  was  due  to  training.  The  other 
answer  would  involve  both  influences,  attributing  part  to 
heredity  and  part  to  training;  if  this  were  the  case,  the 
problem  would  be  complicated  by  determining  what  the 
share  of  each  might  be.  The  evidence  is  largely  suppUed 
by  statistical  studies. 

Most  work  has  been  done  upon  the  origin  of  intelligence. 
The  lack  of  intelligence  or  feeble-mindedness  seems,  from 
Goddard's  results,  to  be  a  recessive  trait,  which  follows  the 
laws  of  MendeHan  inheritance  quite  as  accurately  as  do  the 
transmission  of  colors  in  plants,  or  shagginess  in  the  guinea 
pig.  Goddard  traced  this  trait  in  several  hundred  families 
in  New  Jersey  and  found  that  one  could  predict  the  appear- 
ance of  feeble-mindedness  in  the  children  with  the  same 
accuracy  that  one  could  predict  the  shape  of  the  leaf  from 
crosses  of  plants. 

Studies  of  the  inteUigence  of  school  children  by  the  Binet 
tests  indicate  that  the  intelligence  of  children  who  come  from 
the  better  homes  is  about  a  year  higher  on  the  average  than 
is  that  of  those  who  come  from  poorer  homes.  One  might 
attribute  this  to  training  as  well  as  to  inheritance.  If  we 
assume  that  the  individual  with  the  better  home  and  social 
standing  is  more  intelligent  and  has  reached  his  position 
because  of  that  intelligence,  the  parent  who  is  responsible 
for  the  heredity  of  the  child  is  also  responsible  for  his  training. 
That  it  is  heredity  rather  than  training  is  shown  from  the  fact 
that  occasionally  one  will  find  a  child  of  high  intelligence  in  a 
poor  home,  while  placing  the  child  of  unintelligent  parents 
under  the  best  of  training  will  not  increase  his  intelligence. 


INDIVIDUAL  DIFFERENCES  211 

Studies  of  heredity  as  shown  in  the  biographies  of  eminent 
men  indicate  not  merely  that  intelligence  in  general  is 
inherited,  but  also  that  specific  types  of  intelligence  are 
transmitted.  Gal  ton  traced  the  ancestry  and  descendants 
of  eminent  Britons  of  all  calHngs,  and  found  that  children 
of  distinguished  men  had  a  very  much  greater  chance  of 
being  eminent  themselves  than  did  the  child  of  average 
parents.  Sons  of  justices  were  hkely  themselves  to  be  dis- 
tinguished jurists,  sons  of  distinguished  scientists  were 
likely  to  be  scientists  of  high  rank,  and  children  of  artists 
were  frequently  successful  in  art.  Wood,  in  a  similar  study 
of  royal  personages,  found  marked  tendencies  to  the  inherit- 
ance of  abihties  and  of  defects.  One  might  argue  that  the 
specific  direction  of  the  interests  of  the  child  of  the  com- 
moner might  be  dependent  upon  hving  with  the  parents 
and  the  opportunities  that  were  implied  by  that.  Un- 
doubtedly there  is  some  element  of  environment  included 
in  the  influences  that  determined  the  men  whom  Galton 
studied.  In  royalty  this  factor  would  be  reduced,  since, 
so  Wood  argues,  the  environment  for  all  royal  children  is 
approximately  the  same.  Nevertheless  the  traits  of  the 
parents  can  be  traced  very  clearly  in  the  offspring  through 
a  number  of  generations. 

Another  statistical  study  of  inheritance  by  Pearson  con- 
firms the  result.  Pearson  asked  teachers  in  all  parts  of 
England  to  estimate  the  standing  of  brothers  and  sisters 
with  reference  to  easily  described  traits,  and  then  calcu- 
lated the  coefficient  of  correlation  for  the  traits  in  pairs  of 
brothers  and  sisters.  He  included  ability,,  vivacity,  con- 
scientiousness, temper,  and  assertiveness,  among  his  traits. 
He  found  a  coefhcient  of  correlation  between  children  of  the 
same  parent  of  about  0.50.  This  is  approximately  the  same 
as  the  coefficient  for  different  physical  measurements.    In 


212        FUNDAMENTALS   OF   PSYCHOLOGY 

the  rough,  it  means  that  mental  characters  are  as  Hkely  to 
be  inherited  as  are  physical  characters.  It  will  be  noticed 
that  several  of  his  traits  belong  in  the  emotional  and  voU- 
tional  group.  This  so  far  tends  to  confirm  common  observa- 
tion that  these  are  inherited  as  well  as,  and  in  approximately 
the  same  degree  as,  the  intellectual  differences.  Taken  to- 
gether the  evidence  is  conclusive  that  differences  in  mental 
capacities  and  in  volitional  and  emotional  disposition  are 
specific  heredities  from  the  immediate  parents. 

Habit  Formation 

Instinct  and  Habit.  —  On  the  other  hand  there  are  groups 
of  characteristics  which  are  also  inherited  that  contribute 
to  make  the  individuals  similar.  These  are  the  instincts. 
While  present  in  different  degrees  in  different  individuals, 
they  are  represented  in  all  individuals  and  may  be  con- 
sidered the  factors  that  serve  to  produce  uniformity  in  the 
race  as  a  whole.  Very  briefly  we  may  assert  that  similarity 
in  response  to  the  same  stimulation,  the  similarities  in  aims 
and  in  mental  activities  when  not  due  to  similar  education 
or  to  Hving  in  the  same  environment,  are  to  be  ascribed  to 
instinct.  These  instinctive  responses  range  from  those  which 
are  fundamental  to  the  life  of  the  organism  and  serve  to  keep 
the  individual  alive  until  he  learns  to  take  care  of  himself,  to 
the  appreciation  of  the  essential  or  desirable  in  external 
stimulation  and  in  his  own  aims.  The  definite  study  of  the 
instincts  in  their  origin  and  effects  we  may  leave  to  the 
next  chapter.  Suffice  it  here  to  indicate  that  there  are  these 
movements  and  forces  in  the  control  of  behavior  and  mental 
life  in  general  which  are  due  to  the  connections  innate  in 
the  nervous  system.  In  discussing  the  reflexes  in  the 
chapter  on  the  nervous  system,  it  was  seen  that  the  simple 
actions  were  determined  by  the  ready-made  connections 


INSTINCT  AND   HABIT  213 

between  different  neurones  at  the  synapses.  The  instincts 
have  the  same  general  explanation.  They,  too,  are  the 
result  of  the  openness  of  synapses  at  birth.  The  difference 
between  the  two  is,  first,  that  the  instinct  is  usually  a  larger 
group  of  movements  tied  together  in  a  single  complex 
whole;  secondly,  that  the  movements  are  characterized 
by  their  cooperation  to  the  attainment  of  a  definite  end; 
and  in  the  third  place,  the  movements  involved  in  the 
instinct  may  be  more  variable,  the  end  is  apparently 
determined,  but  the  movements  by  which  the  end  is  at- 
tained may  be  varied  with  the  circumstances  or  through  the 
learning  of  the  individual. 

The  Formation  of  Habits.  —  The  other  factor  in  the  life 
of  the  individual  which  requires  preliminary  mention  here 
is  the  formation  of  habits.  On  the  motor  or  behavior  side 
this  is  the  complement  of  instinctive  activity.  Certain  of 
the  movements  of  the  organism  are  as  fixed  as  the  move- 
ments of  a  machine,  at  least  of  a  machine  that  is  loose  in 
the  gearings  and  as  wobbly  and  uncertain  in  its  movements 
as  the  worst  conceivable  machine  that  will  run  at  all.  By 
far  the  greater  number,  however,  are  adjusted  to  the  sepa- 
rate stimuH  by  a  series  of  tentative  movements,  and  become 
fixed,  if  at  all,  only  after  a  number  of  trials.  The  higher 
the  animal,  on  the  whole,  the  smaller  the  proportion  of 
responses  that  are  determined  by  instinct  and  the  larger 
the  number  that  must  be  acquired  by  the  individual  him- 
self. 

Learning  is  by  Trial  and  Error.  —  This  process  of  learn- 
ing is  always  by  a  series  of  trials  with  numerous  failures  and 
long-delayed  successes  which  only  gradually  approximate 
the  end  desired.  This  is  known  as  the  process  of  trial  and 
error.  Fundamentally  it  is  probable  that  each  separate 
movement  is  prepared  by  an  open  connection  or  connections 


214 


FUNDAMENTALS   OF   PSYCHOLOGY 


in  the  nervous  system.  However,  so  many  paths  are  open 
that  many  different  responses  are  made  in  succession  to  the 
same  stimulus,  and  the  apparent  result  is  that  chance 
determines  what  the  first  reaction  shall  be  and  the  order  in 
which  it  shall  be  followed  by  other  responses. 

Studies  on  animals  under  experimental  conditions  indicate 
very  clearly  the  nature  of  the  process.  If  a  hungry  cat  be 
put  into  a  box  with  a  door  supplied  with  a  catch  which 
can  be  opened  from  the  inside,  and  a  bit  of  fish  placed  near, 
the  following  series  of  learning  processes  will  be  noted  in 
typical  cases.  Biting  the  catch,  and  biting  without  definite 
object  near  the  door  and  at  all  other  places  that  look 
promising,  will  be  succeeded  by  scratching,  and  even  by 
cries.  Sooner  or  later  some  one  of  these  movements  is 
pretty  sure  to  open  the  door  and  permit  the  cat  to  walk  out. 
Learning  in  animals  is  seldom  complete  with  one  per- 
formance. If  the  cat  be  put  back,  it  will  have  to  go  through 
a  similar  series  of  uncertain  movements  before  it  gets  out 
again.  The  time  required  for  escape  will  be  lessened  at 
each  trial,  until  finally  it  will  make  the  correct  response  as 
soon  as  it  is  put  into  the  cage.' Learning  by  the  child  also 
follows  the  method  of  trial  and  error.  When  the  baby  learns 
to  creep,  the  first  movement  is  by  chance.  Some  children 
make  their  first  movements  by  hitching  forward  as  they 
sit  up.  If  this  is  repeated  sufficiently  often  it  may  become 
established  as  a  habit,  and  unless  the  regular  crawHng  move- 
ment or  some  other  more  effective  means  of  locomotion 
happens  to  be  hit  upon,  the  child  may  use  that  alone  until 
he  learns  to  walk.  Some  children  hit  first  upon  the  series 
of  movements  that  will  push  them  backwards  —  occa- 
sionally one  will  develop  the  habit  of  rolling  over.  Which- 
ever develops  first  will  be  used  until  a  new  and  more  satis- 
factory method  is  hit  upon.    In  many  cases  the  first  method, 


INSTINCT  AND   HABIT  215 

even  if  awkward,  will  be  continued  until  the  child  begins 
to  learn  to  walk. 

^  This  trial  and  error  method  is  followed  in  the  acquirement 
of  every  kind  of  movement;  it  persists  to  the  acquisition 
of  the  most  important  and  complicated  movements  of  adult 
life.  From  these  simplest  first  movements  through  to 
learning  a  complicated  industrial  process  or  a  new  game  of 
skill,  the  process  of  learning  is  one  of  chance  movements 
and  elimination  of  the  unsuccessful  attempts. 

Learning  as  a  Nervous  Process.  —  If  we  analyze  the 
mechanism  of  the  process  a  little  more  closely,  we  can  see 
that  the  requirements  are:  first  that  the  individual  shall 
have  a  large  number  of  possible  movements  at  command  and 
shall  know  when  the  desired  object  is  attained,  or  possibly 
shall  have  the  capacity  for  discriminating  between  the 
beneficial  and  non-beneficial,  either  in  advance  of  the 
movement  or  after  the  result  has  been  gained.  The  first 
capacity  is  due  to  the  spread  of  the  impulse  from  the  sen- 
sory neurones  first  aroused  to  as  many  motor  neurones  as 
possible.  This  spread  through  the  untrodden  ways  of  the 
cerebral  cortex  is  very  much  like  the  formation  of  associa- 
tion, save  that  there  is  not  even  the  simultaneous  activity 
of  some  other  area  to  guide  the  course.  Every  impulse  of 
even  moderate  strength  seems  to  pass  over  into  motor 
discharge.  When  a  sensory  neurone  or  group  of  sensory 
neurones  is  aroused,  the  impulse  tends  to  spread  to  motor 
paths,  even  if  there  has  been  no  previous  excitation  of  that 
group  of  neurones  or  sense  organs.  It  has  sometimes  been 
suggested  that  each  response  must  have  been  developed  in 
the  brain  previous  to  birth,  —  must  be  in  part  of  instinctive 
origin,  —  but  the  number  of  apparently  new  combinations 
makes  it  seem  that  many  parts  of  the  cortex  have  open 
pathways  between  them  over  which  the  impulse  may  take 


2i6         FUNDAMENTALS   OF  PSYCHOLOGY 

its  course.     The  many  alternative  paths  make  learning 
possible. 

Selection  of  Habits  Determined  by  Instincts.  —  When 
a  stimulus  affects  the  sense  organ,  one  group  or  series  of 
synapses  after  another  will  be  opened,  and  a  corresponding 
movement  made,  until  a  more  satisfactory  condition  is 
attained;  that  is,  until  the  stimulus,  if  unpleasant,  has 
been  removed  or  a  more  complete  stimulation  by  a  pleasant 
stimulus  has  been  obtained.  These  successive  paths  are 
opened  in  the  order  of  permeabihty  of  the  synapses.  The 
determination  of  what  response  shall  be  accepted  and 
repeated  until  it  becomes  a  habit  is  the  essential  phase  of 
the  whole  process.  The  selection  is  fundamentally  innate 
or  instinctive  in  character.  What  shall  seem  suitable  to 
the  individual  depends  upon  his  inherited  disposition, 
influenced  to  some  extent  possibly  by  his  training.  When 
the  result  of  a  movement  is  pleasing,  either  in  general  or  in 
the  particular  setting  in  which  it  occurs,  it  will  be  repeated. 
With  repetition  it  will  become  a  habit.  In  this  way  the 
control  of  habit  formation  is  exercised  through  instinct. 
Since  many  movements  that  are  ordinarily  called  instincts 
are  not  perfect  at  the  first  performance  and  need  a  number 
of  trials  before  they  reach  perfection,  it  is  evident  that 
most  of  what  we  call  instincts  are  definitely  similar  to  these 
habitual  processes.  Both  belong  to  the  same  class,  but  he 
at  opposite  extremes.  All  movement  depends  upon  both 
instinct  and  learning.  One  element  may  greatly  predomi- 
nate over  the  other.  After  the  response  that  gains  satis- 
factory results  chances  to  be  made,  it  will  be  repeated  until 
the  synapses  that  lead  to  it  will  be  more  completely  open 
than  any  of  the  others.  When  the  habit  of  making  this 
response  is  established  the  particular  movement  will  always 
respond  to  the  given  stimulus. 


INSTINCT  AND    HABIT  217 

Pleasure  a  Guide  to  Learning.  —  The  modus  operandi 
of  the  instinct  in  the  formation  of  habit  is  not  altogether 
agreed  upon. '  In  part  it  seems  that  the  mere  pleasantness 
of  the  result  itself  serves  to  faciUtate  learning  and  so  leads  to 
habit  formation.    At  times  it  seems  that  the  mere  pleasant- 
ness makes  a  response  whose  result  is  pleasing  more  likely 
to  be  repeated,  and  so  the  learning  is  due  to  the  frequency 
.of  repetition  alone.     In  other  instances  it  seems  that  the 
pleasure  itself  serves  to  make  the  pleasant  response  more 
permanent,  to  have  a  greater  effect  upon  the  synapses  than 
the  unpleasant.    Certain  it  is  that  the  pleasant  response 
becomes  estabhshed,  while  the  unpleasant  is  ehminated. 
One  element  in  the  process  may  be  the  frequency  of  repeti- 
tion when  a  stimulus  recurs  that  has  evoked  a  response  with 
a  pleasant  result.    The  old  pleasure-giving  movement  will 
be  repeated,  while  the  unpleasant  response  evoked  by  a 
stimulus  will  be  checked  when  it  reappears  later.     This 
leads  to  a  more  frequent  repetition  of  the  pleasant  response 
than  of  the  unpleasant.     Often  this  takes  the  form  of  one 
movement  when   the  stimulus  itself  is  pleasant,   and  of 
another  when  it  is  unpleasant.    Usually  withdrawal  comes 
with    displeasure,    approach    with    pleasure.      A    case    of 
opposed  response  is  illustrated  by  the  learning  to  peck  and 
swallow  of  the  moor  chick  reported  by  Lloyd  Morgan.    The 
chick  at  first  pecks  at  all  small  objects.    When  a  disagreeable 
one  reaches  the  mouth  it  is  ejected,  while  the  pleasant  one 
will  be  swallowed.    After  a  time  the  unpleas-ant  will  not  be 
picked  up.    The  unpleasantness  of  the  result  serves  to  pre- 
vent the  pecking  response,  although  the  immediate  effect 
is  to  reject  the  food.    The  t-erms  '  pleasant '  and  '  unpleasant ' 
are  probably  the  mental  accompaniments  of  the  benefit 
and  injury  which  are  instinctively  appreciated. 

This  trial  and  erroir  process,  then,  is  made  possible  by  the 


2i8        FUNDAMENTALS   OF  PSYCHOLOGY 

numerous  potential  connections  in  the  nervous  system  be- 
tween sensory  and  motor  neurones.  It  is  checked  and  con- 
trolled by  the  instinctive  awareness  of  benefit  and  injury 
which  is  revealed  in  the  pleasantness  and  unpleasantness 
of  the  results  of  stimulation  and  of  action.  All  action  is  a 
resultant  of  these  two  processes:  chance  trial  and  control 
by  instinct. 

The  division  of  actions  into  two  distinct  parts,  a  more 
or  less  uncontrolled  evocation  of  the  process  through  chance 
connections  on  the  one  hand,  and  a  control  or  selection  by 
consciousness  of  what  is  suggested,  on  the  other,  is  typical, 
we  shall  find,  of  mental  processes  as  well  as  of  physical. 
Whether  we  be  thinking,  or  recalldng,  or  imagining,  we 
usually  have  a  rather  uncontrolled  and  irregular  series  of 
trials  first,  and  then  gradually  hit  upon  some  movement 
which  is  approved  and  accepted.  We  must  always  dis- 
tinguish between  the  arousal  and  the  acceptance  or  rejection 
of  any  process,  be  it  motor  or  sensory. 

REFERENCES 

Terman:   The  Measurement  of  Intelligence. 

Yerkes  and  Yoakum:   The  Army  Mental  Tests. 

Wood:   Heredity  in  Royalty. 

Galton:   Hereditary  Genius. 

Pearson:  The  Inheritance  of  Mental  and  Moral  Characters. 
Biometrika,  1904,  page  131. 

Webb:  Intelligence  and  Character.  British  Journal  of  Psy- 
chology, Monograph  Supplements,  Vol.  I,  No.  3. 


CHAPTER  VII 
INSTINCT 

We  come  now  to  consider  the  second  form  of  innate 
tendencies  or  capacities  which  determine  the  responses  and 
finally  the  character  of  the  individual.  These  are  the  in- 
stincts. As  opposed  to  intelligence  and  the  general  emo- 
tional and  voluntary  characteristics,  which  are  merely 
capacities  for  larger  groups  of  responses,  instincts  are  either 
specific  responses  or  tendencies  that  control  the  character 
of  the  specific  responses.  They  may  also  be  opposed  to  the 
above  mentioned  group,  they  are  the  endowment  of  the 
race  as  a  whole  rather  than  of  any  family  or  individual. 
They  give  unity  to  the  race,  since  all  men  share  in  the  in- 
stincts, while  intelligence  and  temperament  serve  rather  to 
emphasize  the  differences  of  individuals. 

The  term  '  instinct '  is  used  to  designate  a  large  number  of 
different  processes,  activities  and  tendencies  to  activities. 
So  general  has  been  the  use  of  the  word,  in  fact,  that  some 
writers  desire  to  give  it  up  as  too  vague.  However,  so  many 
important  facts  may  be  grouped  under  the  term,  and  the 
series  of  activities  it  describes  is  so  important,  that  it  seems 
much  better  to  retain  the  word  and  to  state  clearly  just 
what  it  is  and  what  it  is  not  to  mean. 

The  Nature  of  Instinct 

Definitions  of  Instinct.  —  Two  distinct  meanings  of  the 
word  instinct  are  current.  The  first  defines  instinct  as  a 
movement  or  series  of  movements  evoked  by  a  particular 


220        FUNDAMENTALS   OF  PSYCHOLOGY 

stimulus.  The  second  defines  it  in  a  way  to  make  it  Kttle 
different  from  the  learning  by  trial  and  error  mentioned  in 
the  last  chapter.  It  is  constituted  by  a  series  of  tentative 
movements  guided  to  an  end  by  the  pleasures  that  attach 
to  possession,  or  the  discomfort  that  results  from  lack  of 
the  object  or  condition  that  constitutes  the  end.  Here  the 
movements  are  not  prescribed,  in  fact,  vary  greatly  from 
situation  to  situation.  What  is  instinctive  is  the  pleasure 
or  displeasure  which  impels  to  movement  and  assures  the 
attainment  of  the  end. 

The  first  is  used  to  designate  a  more  complicated  re- 
flex. Thus,  the  pecking  at  a  grain  of  corn  by  a  newly 
hatched  chick,  and  the  complicated  series  of  movements 
by  which  it  breaks  its  way  out  of  the  shell,  are  instincts  of 
the  first  type.  An  excellent  illustration  of  the  simple 
instinct  dependent  upon  the  stimulus  and  not  modified  to 
meet  changing  conditions  is  that  of  the  soHtary  wasp 
noticed  by  Fab  re,  and  quoted  by  Hobhouse  as  follows:  "A 
solitary  wasp,  Sphex  flavipennis,  which  provisions  its  nest 
with  small  grasshoppers,  when  it  returns  to  the  cell  leaves 
the  victim  outside,  and  goes  down  for  a  moment  to  see  that 
all  is  right.  During  her  absence  M.  Fabre  moved  the 
grasshopper  a  little.  Out  came  the  Sphex,  soon  found  her 
victim,  dragged  it  to  the  mouth  of  the  cell,  and  left  it  as 
before.  Again  and  again  M.  Fabre  moved  the  grasshopper, 
but  every  time  the  Sphex  did  the  same  thing,  until  M.  Fabre 
was  tired  out."  Instincts  in  this  sense  are  more  compli- 
cated than  the  reflex,  involve  a  greater  number  of  muscles, 
and  a  larger  number  of  movements  in  a  series.  The  line 
between  reflexes  and  instincts  thus  defined  is  difficult  to 
draw.  Just  how  complicated  a  reflex  must  be  to  become  an 
instinct  is  not  easy  to  say.  It  has  sometimes  been  asserted 
that  instincts  are  more  purposive,  reflexes  more  mechanical, 


INSTINCT  221 

but  even  this  distinction  is  not  very  clear,  since  most 
reflexes  as  well  as  instincts  have  a  purpose  even  if  reflexes 
are  explained  by  mechanism.  Again,  there  is  always  an 
implication  in  instinct  that  we  are  deahng  with  something 
that  is  or  might  be  conscious,  that  is  like  voluntary  action. 
But  this  is  mostly  an  analogy,  and,  since  instincts  are  very 
frequently  not  conscious,  or  we  can  only  infer  that  they  are 
conscious,  even  this  criterion  is  not  susceptible  of  accurate 
application.  Instinct  in  this  sense  is  a  movement  made  in 
response  to  a  stimulus  or  a  group  of  stimuH  as  a  result  of 
inherited  connections  in  the  nervous  system,  a  movement 
more  compHcated  than  a  reflex,  either  in  the  number  of 
stimuli  that  call  it  out,  or  in  the  number  of  muscles  that  are 
coordinated  in  its  execution.  In  many  minds,  but  subordi- 
nate to  this  distinction,  is  the  further  implication  that  the 
instinct  is  purposive,  and  more  like  voluntary  or  conscious 
movement  than  the  reflex. 

Variation  in  Instinct.  —  As  opposed  to  this  rigidly  deter- 
mined series  of  movements,  most  instincts  show  considera- 
ble variation  and  reach  the  final  end  by  various  ways.  The 
hunting  instinct  of  a  cat,  as  exhibited  in  catching  and  killing 
mice  or  birds,  adapts  itself  to  the  circumstances.  Only  the 
crouching  as  the  prey  is  approached  and  perhaps  the  final 
spring  are  even  approximately  uniform.  The  cat  usually 
plays  with  the  mouse  after  it  is  caught,  but  even  this  is  not 
a  mere  mechanical  repetition  of  the  same  movement  or 
series  of  movements.  The  resemblance  between  acts  at 
different  rimes  is  at  best  general.  The  reaction  is  to  a 
number  of  separate  stimuli  each  of  which  calls  out  a  separate 
act,  and  the  whole  series  is  bound  together  by  the  general 
end.  Probably,  even  here,  each  separate  act  is  the  result  of 
a  definite  stimulus,  but  the  connecting  Hnk  that  makes  the 
whole  a  unit  is  found  in   the  preparedness   induced   in 


222        FUNDAMENTALS   OF  PSYCHOLOGY 

the  animal  by  one  act  which  makes  it  more  readily  affected 
by  a  stimulus  of  the  same  group  rather  than  by  any  other. 
The  whole  may  be  pictured  as  held  together  by  an  inherited 
tendency  for  the  acts  of  the  entire  series  to  respond  in  suc- 
cession to  definite  sorts  of  stimuli.  But  there  is  much 
variety  in  the  way  in  which  the  end  is  reached,  due  appar- 
ently to  the  fact  that  instead  of  preparing  the  way  for  one 
set  of  responses  alone,  a  number  of  responses,  eac'h  of  which 
may  lead  to  the  desired  end,  are  rendered  more-  easy. 
Whenever  a  stimulus  presents  itself  that  excites  any  of  the 
group  of  movements,  the  way  is  opened  for  carrying  out  all 
the  others. 

Instincts  as  Ends.  —  Instinctive  activities  of  the  second 
class  are  still  less  definite  in  character.  In  the  extreme  in- 
stances of  this  class  little  is  determined  by  inheritance 
other  than  that  the  desired  end  shall  be  attained.  The 
attainment  may  be  by  any  method  that  previous  experience 
or  the  acquired  habits  shall  dictate.  The  desire,  not  the 
movement,  is  instinctive.  In  this  second  class  belong  very 
many  if  not  most  of  the  comphcated  instincts  manifested 
by  the  human  adult.  Acquisitiveness,  combativeness, 
sympathy,  and  the  great  mass  of  instincts  that  may  be 
regarded  as  protecting  the  human  individual,  the  family, 
and  the  social  group,  are  constituted  of  movements  that 
have  no  regularity,  but  nevertheless  drive  the  individual  to 
a  fairly  definitely  prescribed  end.  Thus,  we  speak  of  mating 
as  an  instinct,  but  the  preliminary  instinctive  responses 
of  coyness,  and  the  whole  series  of  courting  activities, 
whether  in  the  higher  animals  or  in  man,  are  indefinite. 
At  the  more  reflex  end  of  this  class  are  movements  that  seem 
to  be  directed  toward  a  definite  end,  but  the  separate 
responses  are  not  each  dependent  upon  the  preceding  act 
and  the  stimulus,  but  are  complex  mixtures  of  learned 


INSTINCT  223 

movements  with  a  few  reflexes.  In  simplest  form  the 
second  class  is  different  from  the  more  general  forms  of  the 
first  only  in  the  fact  that  movement  and  the  stimulus  are 
not  so  closely  joined.  One  of  several  responses  may  be  made 
to  the  stimulus.  Again,  one  movement  of  the  series  does 
not  follow  so  mechanically  upon  the  preceding.  Finally, 
the  end  is  more  in  evidence.  This  end  may  be  foreseen, 
although  the  reason  for  the  dominance  of  that  end  or  pur- 
pose is  usually  not  appreciated.  At  the  other  extreme  of 
this  class,  what  is  instinctive  is  the  pleasure  that  accom- 
panies the  attainment  of  the  purpose  rather  than  the  con- 
catenation of  movements  that  shall  lead  to  that  end.  The 
acts  made  when  one  sees  a  beggar  may  vary  from  giving 
money  to  turning  away  as  quickly  as  possible,  but  the  feel- 
ing of  pain  that  impels  to  some  action  is  due  to  inherited 
causes. 

The  term  instinct,  then,  is  used  to  indicate  all  acts  whose 
conditions  are  inherited.  It  matters  not  whether  those  acts 
may  be  referred  to  specific  inherited  connections  in  the 
nervous  system  or  whether  the  act  is  the  result  of  striving 
for  an  end  which  some  innate  predisposition  compels  the 
individual  to  strive  for,  and  whose  attainment  gives 
pleasure.  While  this  definition  is  broader  than  that  ex- 
plicitly given  by  many  psychologists,  all  extend  the  term 
in  practice  to  cover  acts  that  belong  only  to  our  broadest 
class.  At  present  most  men  incline  to  make  instincts 
primarily  reflexes  of  greater  complexity,  and  to  reduce  as 
many  as  possible  to  the  simpler  forms  of  response.  This  is 
the  more  satisfactory,  as  it  reduces  to  a  minimum  the  nat- 
ural tendency  to  vagueness  and  the  introduction  of  mystical 
forces.  Even  where  instincts  cannot  be  explained  in  this 
simplest  way,  there  is  no  need  to  resort  to  the  mystical, 
since  the  dispositions  and  preparatory  irradiations  may  all 


2  24        FUNDAMENTALS   OF  PSYCHOLOGY 

be  assumed  to  be  due  to  the  inheritance  of  specific  disposi- 
tions in  the  nervous  system,  even  if  we  cannot  at  present 
say  exactly  in  what  they  consist. 

Specific  Instincts 

Classification  of  Instincts.  —  The  specific  instincts  are 
differently  classified,  and  no  complete  agreement  exists  as 
to  what  shall  be  regarded  as  instinctive,  even  when  the 
definitions  have  been  settled.  MacDougall  limits  instincts 
to  flight,  repulsion,  curiosity,  pugnacity,  self-abasement, 
self-assertion,  and  the  parental  instinct  (under  which  are 
placed  care  of  the  child,  sympathy  as  an  outgrowth  of  care 
for  the  offspring,  and,  by  development,  moral  indignation). 
Minor  instincts  are  reproduction,  gregarious  instincts,  con- 
struction. Watson  in  his  study  of  animals  has  eleven 
classes,  —  locomotion,  obtaining  food,  shelter,  rest,  play, 
sleep,  taken  together  as  the  basis  for  the  daily  and  seasonal 
routine;  sex,  defence  and  attack,  migration,  mimicry, 
vocalization;  and  two  less  definite  groups.  It  can  be  seen 
that  almost  all  of  MacDougall's  fist  belong  to  our  second 
class.  Watson's  are  fairly  evenly  divided  between  the  two. 
Some  add  more,  others  question  some  of  these,  but  there  is 
probably  no  chance  of  close  agreement  among  all  as  to  just 
how  many  groups  there  are,  or  even  what  specific  acts  shall 
be  included  in  any  group. 

It  will  be  best  to  make  a  general  classification  with 
reference  to  the  end  that  the  act  subserves,  rather  than  to 
the  specific  character  of  the  particular  instinct.  One  of 
the  most  convenient  divides  instincts  into  three  classes: 

1.  Those  which  preserve  the  Ufe  and  provide  for  the 
welfare  of  the  individual; 

2.  Those  which  provide  for  the  continuance  of  the 
race  and  for  the  family; 


CLASSIFICATION  OF   INSTINCTS  225 

3.  Those  which  make  for  the  welfare  of  the  tribe  or 
of  the  social  unit. 

Some  of  the  acts  belong  to  more  than  one  class,  —  in 
fact,  no  one  of  the  second  or  third  would  be  possible  without 
the  first,  —  but  the  division  is  convenient  in  general  and 
may  serve  as  a  guide  through  the  maze. 

Individual  Instincts.  —  Among  the  individual  instincts 
we  have  those  necessary  for  the  care  of  the  individual  in 
the  early  stages  of  life.  One  of  the  best  instances  is  found  in 
the  pecking  its  way  out  of  its  shell  by  the  young  bird.  This 
instinct,  according  to  Craig,  is  always  carried  out  in  very 
much  the  same  way,  although  involving  two  important 
separate  movements:  pecking  itself,  and  so  turning  in  the 
shell  that  the  shell  may  be  broken  in  a  continuous  ring. 
Here,  too,  belong  the  first  movements  of  taking  food,  which 
make  their  appearance  ahnost  at  once,  and  change  their 
character  as  the  needs  of  the  organism  develop.  Other 
individual  instincts  are  involved  in  locomotion,  walking, 
flying,  or  swimming,  the  care  of  the  body  in  matters  of 
cleanliness,  the  preening  of  the  feathers  by  the  bird,  licking 
the  body  by  cats,  dogs,  etc.,  the  persistent  hunt  for  para- 
sites that  seems  to  occupy  a  large  part  of  the  spare  time  of 
all  monkeys  and  apes,  stalking  game,  fighting,  flight  from 
larger  animals,  in  sum  an  imposing  fist. 

Instincts  of  Human  Infancy.  —  In  a  recent  careful  study 
of  several  hundred  infants  in  the  maternity  ward  of  The 
Johns  Hopkins  Hospital,  Watson  found  that  the  number 
of  instincts  exhibited  by  infants  up  to  200  days  was  much 
smaller  than  is  usually  thought.  He  found  only  crying, 
nursing,  grasping,  movements  of  defence,  eye-coordination, 
blinking,  manipulation,  and  fears  of  falling  and  of  loud 
sounds.  The  child  from  birth  can  support  itself,  will  push 
away  an  object  that  injures  it,  and  will  feel  about  and  inves- 


226        FUNDAMENTALS   OF  PSYCHOLOGY 

tigate  any  object  that  it  can  reach.  On  the  other  hand, 
Watson  saw  no  evidence  of  instinctive  swimming  move- 
ments, of  right-handedness,  nor  of  withdrawal  from  filth. 
It  is  not  claimed  that  some  of  the  more  complex  instincts 
may  not  appear  at  later  periods,  but  at  the  later  period  they 
would  be  mixed  with  learning  and  would  probably  belong  in 
the  class  of  instincts  which  are  determined  by  the  desirable- 
ness of  the  end,  rather  than  of  simple  predetermined 
movements.  It  appears  certain  that  the  purely  instinctive 
movements  are  relatively  few  in  man. 

Fears.  —  The  more  highly  developed  and  complicated 
acti\ities  of  the  adult  are  many  of  them  guided  merely 
by  the  instinctive  pleasantness  of  the  end  sought  or  the 
instinctive  disagreeableness  of  the  object  avoided.  This 
is  true  in  large  degree  of  the  responses  in  fear,  although 
some  of  the  movements  are  fairly  constant  and  common  to 
many  men.  They  show  themselves  in  practically  all  men, 
although  to  be  sure  in  different  forms  and  in  different 
degrees.  In  most  cases  they  are  not  to  be  explained  from 
experience,  and  many  are  absurd  in  the  light  of  experience. 
Why  a  grown  woman  should  be  so  startled  by  a  mouse,  why 
a  man  should  make  such  exaggerated  responses  when  a 
harmless  snake  wraps  itself  around  his  ankle,  are  hard  to 
understand  in  the  light  of  experience  alone.  Similar  are 
the  trembling  at  looking  over  the  edge  of  a  precipice  from 
behind  a  perfectly  secure  raihng,  the  fear  of  the  dark,  of 
caves  and  strange  places,  of  the  dead,  and  hosts  of  others 
that  the  reader  may  supply  from  his  own  experience.  In 
the  development  of  a  child,  these  fears  come  one  after 
another  and  frequently  disappear  almost  as  suddenly  as 
they  appear.  For  a  few  weeks  or  months  a  child  will  be 
afraid  of  fur,  then  the  fear  disappears  and  fondness  for  it 
replaces  the  fear.    A  cat  may  suddenly  become  an  object 


CLASSIFICATION  OF   INSTINCTS  227 

of  terror,  and  later,  without  other  experience  of  cats,  may- 
arouse  all  signs  of  pleasure.  Thus,  the  early  life  may  be  a 
constant  succession  of  fears  that  come  apparently  with  the 
stages  of  development  of  the  nervous  system.  Interesting, 
too,  it  is  to  note  the  tendency  of  those  fears  to  become 
exaggerated  in  diseased  conditions  of  the  central  nervous 
system.  Here  we  find  fear  of  opeiLplaces  that  leads  the 
victim  to  slink  around  the  sides  of  parks  rather  than  walk 
across  them  (agoraphobia),  and  also,  the  opposite  tendency, 
to  feaT^ll_closecLplaces,  to  avoid  rooms  and  narrow  streets, 
and  to  feel  at  home  only  in  the  open  (claustrophobia). 
These  are  but  two  of  many  morbid  fears. 

Among  the  instincts  that  aid  to  make  up  the  individual 
character  by  the  amount  they  contribute  to  the  sum  total 
of  his  instincts  are  pugnacity,  the  tendency  to  accumulate, 
and  curiosity.  The  degree  of  pugnacity  is  one  of  the  most 
important  individual  characteristics.  It  varies  from  the 
extreme  in  a  tendency  to  domineer  over  ever>'  one,  through 
a  moderate  degree  of  self-assertion,  to  a  minimum  in  the 
weakling  who  never  asserts  himself.  The  one  man  never 
admits  that  he  is  wrong,  will  never  see  that  he  is  beaten, 
but  fights  on  to  the  end.  Tempered  with  proper  discrimi- 
nation of  what  is  worth  fighting  for,  this  constitutes  one 
of  the  elements  in  all  strong  characters;  untempered,  it 
makes  the  quarrelsome  bully.  The  man  in  whom  it  is 
badly  developed  is  ready  to  give  up  with  the  first  disappoint- 
ment, if  he  permits  himself  to  get  involved  at  all.  Closely 
related,  if  not  identical,  are  the  quahties  of  courage  and 
cowardice.  The  collecting  instinct  is  not  quite  so  clearly 
demonstrable  as  an  instinct,  but  the  piling  up  of  hoards  of 
all  kinds  beyond  the  probable  or  even  the  possible  needs  of 
an  individual  seems  to  demand  an  explanation  other  than 
habit  or  reason.    The  intense  pleasure  which  comes  with 


2  28        FUNDAMENTALS   OF  PSYCHOLOGY 

the  large  accumulation  is  indicative  of  other  than  acquired 
characteristics. 

Curiosity  is  a  striking  character  in  the  attitude  of  the 
higher  animals  as  well  as  of  men.  The  dog,  the  cat  in  less 
degree,  monkeys  in  the  extreme,  show  a  tendency  to  exam- 
ine all  strange  objects.  From  their  acts  one  might  argue 
that  they  were  intent  on  understanding  them.  Certainly 
in  man  there  is  a  pervading  restlessness  until  all  unfamiliar 
objects  and  movements  have  been  examined  and  explained, 
—  an  instinct  that  shows  itself  early  and  persists  with  in- 
creasing intensity  until  well  into  old  age.  In  its  simple 
forms  in  the  child  or  in  the  uncultivated  it  impels  an  investi- 
gation of  all  possible  sources  of  danger  and  provides  for  the 
security  of  the  individual.  In  its  higher  forms  it  may  well 
be  regarded  as  the  source  of  very  much  of  man's  desire  for 
knowledge  and  of  the  growth  of  science  developed  from  it. 
Much  of  this  knowledge  is  probably  useless  from  the 
practical  man's  standpoint,  and  in  any  case  the  investiga- 
tions that  lead  to  the  discoveries  are  most  frequently  carried 
out  for  the  sake  of  the  knowledge  itself,  rather  than  from 
any  intention  of  obtaining  practical  benefit.  The  back- 
ground and  foundation  of  the  individual's  character  are  to 
be  explained  in  large  measure  from  the  degree  in  which  he 
possesses  different  instincts.  They  determine  in  some  meas- 
ure what  shall  appeal  to  him  and,  in  still  larger  measure, 
the  amount  of  effort  that  he  devotes  to  attaining  the  end 
that  appeals. 

Race  Instincts.  —  No  less  important  in  the  adult  Hfe  are 
the  race  instincts.  The  mating  instincts  give  illustration 
both  of  the  definite  but  complicated  response,  and  of  the 
vaguer  movements  determined  only  as  to  their  end,  or  even 
by  the  pleasure  that  comes  from  the  attainment  of  a  given 
purpose,  with  little  control  of  the  method  of  attainment. 


SOCIAL  INSTINCTS  229 

The  manner  of  the  manifestations  of  the  courting  impulses 
is,  in  man,  not  at  all  a  matter  of  conscious  purpose.  The 
display  and  boastfulness  of  the  male  on  the  one  hand,  or 
his  bashfulness  in  the  presence  of  a  chosen  member  of  the 
opposite  sex,  on  the  other,  is  in  most  cases  not  intentional, 
and  cannot  be  prevented  at  will.  The  coyness  of  the  maiden 
is  equally  removed  from  voluntary  control.  Even  more 
widespread  in  their  effect  upon  society  are  the  activities 
and  feelings  involved  in  the  care  of  the  young  and  in  keeping 
together  the  family.  In  man  these  processes  are  largely 
indefinite.  They  are  guided  by  the  pleasure  of  the  parent 
in  the  welfare  of  the  child.  Most  of  the  actual  movements 
are  learned  through  education  and  developed  by  habit. 
Only  the  pleasure  produced  by  the  achievement  of  the  end 
and  by  the  presence  of  the  child  is  really  instinctive;  the 
rest  is  habit.  In  the  lower  animals  of  course  the  instincts 
are  much  more  definite,  as  in  the  building  of  the  nest,  in 
determining  the  kind  of  food  that  is  given,  and  the  way  it 
shall  be  given.  Even  here,  however,  much  is  left  to  the 
control  of  circumstances,  for  the  processes  cannot  be  reduced 
to  a  mere  chain  of  reflexes.  In  man  the  continuous  asso- 
ciation and  the  care  for  the  welfare  of  the  members  of  the 
family  constitute  an  important  element  in  the  development 
of  unselfishness  in  general  and  of  all  the  ideal  elements  in 
character. 

Social  Instincts.  —  The  widest  group  of  instincts,  the 
social,  are  least  often  expressed  as  definite  responses  on  the 
level  of  reflexes,  and  most  frequently  are  merely  goals  im- 
posed by  feelings  of  pleasure  or  the  reverse.  The  most 
primitive  of  the  social  instincts  is  simple  gregariousness. 
This  is  shown  in  its  purest  form  in  the  lower  animals,  but 
is  not  without  its  analogues  in  man.  The  bison  or  reindeer 
or  the  wolf,  under  certain  circumstances,  seems  to  feel 


230        FUNDAMENTALS   OF  PSYCHOLOGY 

pleasure  in  merely  being  with  others  of  his  species.  The 
same  instinct  may  be  seen  in  men  who  feel  pleasure  in  being 
in  the  crowd  on  a  city  street,  even  if  there  be  no  words 
spoken  and  no  intercourse  of  any  kind  with  the  members 
of  the  crowd.  One  may  be  absolutely  alone,  even  avoid 
conversation  with  his  fellows,  and  at  the  same  time  feel 
pleasure  at  their  presence,  or  at  least  feel  a  haunting  and 
unconquerable  loneUness  when  away  in  the  wilderness  or 
where  his  fellows  are  not  to  be  found.  Obviously  this 
instinct  finds  no  simple  expression  in  action,  but  is  due 
merely  to  the  pleasant  feehng  of  being  with  others  or  to 
the  displeasure  of  being  alone.  The  individual  may  and 
usually  does  definitely  plan  the  movements  that  will  take 
him  to  a  place  where  people  are  Hkely  to  be  found,  but  the 
tendency  to  dwell  fondly  upon  the  idea  is  instinctive,  as  is 
also  the  restlessness  that  may  persist  without  awareness  of 
its  cause  until  other  human  beings  chance  to  come. 

More  active  is  sympathy  which  compels  us  to  suffer 
with  those  who  suffer  even  if  we  are  jealous  of  those  who 
rejoice.  It  is  this  that  makes  for  self-sacrifice  in  all  of 
its  forms  in  behalf  of  those  beyond  the  immediate  family; 
it  prevents  cruelty  on  our  own  part  and  enforces  giving 
aid  to  those  who  suffer  at  the  hands  of  others  or  as  the 
result  of  natural  forces.  It  can  be  seen  in- the  gregarious 
animals  who  exert  themselves  and  even  suffer  in  behalf  of 
the  herd,  as  the  male  deer  are  said  to  form  a  circle  about  the 
females  and  the  young  and  to  risk  their  own  lives  in  defence 
of  the  unit.  This  instinct  may  be  justified  teleologically, 
since  the  survival  of  the  individual  and  especially  of  the 
race  depends  upon  the  survival  of  the  larger  group.  In  man 
the  most  striking  feature  of  the  instinct  is  the  limitation  put 
upon  the  group  included  in  its  manifestations.  It  may  and 
has  been  regarded  as  an  extension  of  the  racial  instinct,  the 


SOCIAL   INSTINCTS  231 

instinct  to  protect  the  young,  but  it  includes,  with  a  force 
that  diminishes  with  its  extension,  an  ever-widening  group 
of  individuals.  The  members  of  the  particular  social  set 
stand  next  to  the  family,  then  the  individuals  of  the  same 
class.  The  further  extensions  may  include  the  ever-widen- 
ing circle  of  poHtical  divisions,  it  may  be  drawn  in  some 
degree  in  terms  of  reUgious  or  party  affiliations,  —  in  fact, 
any  common  belief  or  common  purpose  may  serve  as  the 
bond  of  union  within  which  the  instinct  of  sympathy  may 
act.  In  these  divisions  any  common  ideal,  particularly  any 
common  ideal  that  has  opponents,  may  serve  as  the  basis 
for  the  organization  of  a  group  within  which  the  bonds  of 
sympathy  are  effective  against  all  outside  it. 

Sympathy  as  Basis  of  Social  Organization.  —  These  dif- 
ferent lines  of  organization  may  cross  in  many  ways.  One's 
fellows  in  social  position  may  be  opponents  in  politics  or 
religion,  but  the  bonds  of  sympathy  hold  in  one  respect  or 
within  one  group  when  the  same  individuals  are  separated 
in  other  respects.  These  groupings,  with  the  consequent 
feelings,  constitute  the  essential  facts  in  any  understanding  of 
social  organization.  In  the  widest  form,  the  instinct  includes 
all  individuals,  and  thus  makes  possible  the  highest  develop- 
ment of  civilization.  Only  in  the  actions  called  out  toward 
members  of  the  accepted  social  group  is  it  possible  to 
assert  that  we  are  dealing  with  an  instinct.  What  shall 
constitute  the  group  within  which  the  instinct  works  is 
determined  almost  altogether  by  education  and  tradition. 
With  mutual  knowledge  and  increasing  numbers  of  common 
interests  the  number  of  individuals  that  may  be  included 
in  a  social  unity  has  grown  beyond  the  bounds  of  any  one 
country.  But  on  the  other  hand,  a  widespread  war  will 
suddenly  make  rearrangements  of  this  grouping,  will  put 
beyond  the  pale  many  individuals  who  have  up  to  that 


232        FUNDAMENTALS   OF   PSYCHOLOGY 

moment  been  most  intimate  members  of  some  common 
group.  The  strong  bonds  between  the  sociahsts  of  all 
nations  that  existed  before  the  Great  War  were  suddenly 
broken  by  it.  Thus,  while  instinct  determines  the  treat- 
ment of  the  members  of  the  common  unit,  education  and 
experience  determine  who  shall  constitute  the  members. 

Social  Pressure.  —  Not  sympathy  only  but  a  harsher 
set  of  repressing  instincts  also  work  within  these  social 
groups.  The  beginning  of  these  is  fear  of  strangers  and  the 
mass,  which  as  bashfulness  makes  its  appearance  in  early 
youth.  This  persists  with  varying  periods  of  increase  and 
decrease  throughout  Ufa.  This  milder  first  form  of  fear  as 
seen  in  bashfulness  becomes  in  its  more  general  expression 
the  means  of  social  discipline  that  makes  possible  action 
in  the  group.  It  can  be  seen  first  in  the  direct  repressing 
influence  of  the  group  when  physically  present  upon  all  but 
the  leader,  and  on  him  it  acts  more  strongly  than  he  is  wilhng 
to  admit.  One  rises  with  fear,  if  at  all,  to  protest  against 
any  action  of  a  crowd.  Unless  experienced,  a  man  shows 
many  signs  of  fear  as  he  addresses  an  unfamiUar,  even  if 
friendly,  audience.  The  wider  influence  of  the  effects  of 
this  fear  of  social  disapproval  and  pleasure  in  social  ap- 
proval can  be  seen  everywhere  in  social  affairs,  and  in 
many  fields  which  are  not  usually  recognized,  as  social.  It 
is  social  pressure  which  gives  vital  force  to  most  ideals, 
religious  and  moral;  and  which  compels  us  to  follow  styles 
in  thought  as  well  as  in  dress.  One  feels  uncomfortable 
when  clad  in  last  year's  gown,  as  one  does  when  admitting 
adherence  to  an  unpopular  political  party  or  to  a  generally 
condemned  social  theory.  This  is  the  real  social  pressure 
which  compels  conformity  in  every  field.  As  an  active 
force  it  drives  the  individual  in  much  of  his  effort  to  get 
ahead.    It  keeps  the  student  attentive  to  an  uninteresting 


SOCIAL  INSTINCTS  233 

lesson  and  it  impels  the  laborer  or  business  man  to  long 
hours  of  labor  that  shall  enable  him  and  his  family  to  keep 
up  appearances  in  their  own  social  set  or  in  that  to  which 
they  aspire.  These  influences  hold  the  man  to  his  accepted 
place,  keep  him  to  his  allotted  task  in  moments  of  weariness, 
prevent  eccentric  acts  and  remarks,  are  the  forces  that 
make  society  possible,  even  if  in  very  many  cases  they  make 
convention  dominate  originality.  In  the  individual  they 
serve  as  spurs  to  many  of  the  activities  with  a  more  remote 
purpose;  they  give  the  ideal  and  unselfish  aim  an  approxi- 
mation to  equal  standing  with  the  material  and  the  selfish. 

Instinct  and  Conduct 

Instinctive  Conduct.  —  We  may  look  to  instinct  for  an 
explanation  of  many  phases  of  conduct  which  we  cannot 
understand  from  the  immediate  circumstances  or  the  earlier 
education  of  the  individual.  Through  his  instincts  he  is 
spurred  to  the  avoidance  of  dangers  that  he  does  not  know, 
is  impelled  toward  the  attainment  of  rewards  that  he  cannot 
anticipate.  Where  he  recognizes  the  goal  and  the  purpose 
of  the  act,  he  is  impelled,  through  instinct,  to  bodily  reac- 
tions that  he  does  not  understand  and  which  have  no 
apparent  meaning  for  the  act  itself.  He  trembles,  he  weeps, 
he  smiles  and  glows  with  warmth,  adjusts  his  tones  to  the 
mournful  or  the  exultant  key,  all,  so  far  as  he  can  see,  with- 
out reason.  The  insect  lays  its  eggs  and  provides  for  the 
nourishment  and  protection  of  its  young  which  in  many 
cases  it  is  never  to  see.  In  man  the  acts  necessary  for  the 
propagation  of  the  species  are  with  more  knowledge  of 
the  purpose,  but  nevertheless  many  of  the  details  of  conduct 
in  that  connection  can  be  given  no  explanation  from  expe- 
rience alone,  and  the  strength  of  the  impulses  can  be  under- 
stood only  from  forces  beyond  experience,  and  often  opposed 


234        FUNDAMENTALS   OF  PSYCHOLOGY 

to  reason.  Balancing  these  in  many  respects  are  the  social 
instincts  which  enlarge  the  circle  of  objects  of  instinctive 
acts  and  make  the  individual  sensitive  to  the  demands  of 
the  community  with  its  laws  and  traditions. 

Instinct  and  Learning.  —  It  must  be  remembered 
throughout,  that  instincts  never  show  themselves  in  isola- 
tion or  in  pure  form.  They  are  always  mixed  with  the 
reflexes  on  the  one  side,  and  with  habit  and  even  with  reason 
on  the  other.  The  distinction  between  reflex  and  instinct 
is  hard  to  draw.  Even  when  it  has  been  decided  that  an 
activity  belongs  to  the  class  of  instincts,  reflexes  are  always 
present  to  determine  the  execution  of  the  individual  acts. 
Almost  if  not  quite  all  instinctive  acts  are  also  influenced  by 
learning.  Even  so  simple  an  act  as  the  chick's  pecking  at  a 
grain  of  corn  is  not  performed  the  first  time  in  full  perfection 
and,  in  the  more  comphcated  processes,  the  instinctive 
and  experiential  factors  can  with  difficulty  be  isolated. 
In  one  set  of  experiments  the  first  attempts  at  pecking  on 
the  second  day  of  the  chick's  life  gave  ten  correct  responses 
out  of  fifty.  This  increased  to  an  average  of  a  little  less 
than  forty  by  the  seventh  day,  from  which  stage  the  progress 
was  comparatively  slow.  While  mere  growth  with  age  is 
important,  practice  is  necessary  in  ah  cases,  as  is  shown  in 
experiments  by  Breed  and  Shepard.  They  kept  chicks  bhnd- 
folded  for  periods  varying  from  birth  up  to  five  days  and 
found  that  the  number  of  correct  reactions  the  first  day  of 
practice  was  no  greater  for  the  older  than  for  the  younger, 
but  the  older  made  more  rapid  progress.  By  the  eighth  day 
all  were  approximately  on  the  same  level,  irrespective  of  the 
number  of  days  of  practice.  In  the  more  comphcated  acts 
of  the  higher  animals,  instincts  are  still  more  dependent 
upon  training  and  habit  formation.  Birds  kept  in  isolation 
do  not  ordinarily  develop  the  pecuUar  song  of  their  species, 


SOCIAL  INSTINCTS  235 

but  a  new  one.  On  the  other  hand,  where  young  birds  are 
kept  exclusively  with  older  birds  of  another  species,  they 
learn  the  song  of  that  species  within  the  limits  of  their  own 
vocal  capacity.  Even  the  English  sparrow  will  approximate 
the  song  of  canaries  if  kept  near  them  from  birth.  Heredity, 
it  seems,  provides  nothing  but  the  organs  and  the  possibility 
of  forming  suitable  connections,  together  with  the  tendency 
to  use  the  vocal  apparatus  in  any  necessary  way.  All  else 
is  determined  by  the  practice  of  the  individual,  guided  by 
the  sounds  that  are  heard. 

Language  Develops  through  Imitation.  —  In  man, 
instinct  is  still  more  mixed  with  habit  and  all  the  more 
rational  and  voluntary  processes.  Language  is  not  instinc- 
tive as  a  specific  process.  As  in  the  bird,  what  is  instinctive 
is  the  organization  that  makes  sounds  possible,  the  instinct 
of  making  sounds,  with  no  reference  to  the  kind,  and  the 
desire  for  the  approval  of  his  fellows  which  makes  a  child 
desire  to  repeat  the  sounds.  These  together  sufiEice  to  de- 
velop in  the  child  the  language  of  the  people  with  whom  it 
is  thrown,  by  whom  it  is  reared.  Even  the  simplest  instinc- 
tive acts  are  not  performed  at  the  first  trial  in  their  full 
perfection.  Both  practice  and  intelligent  guidance  are 
needed  before  great  accuracy  is  attained.  Here  learning  is 
hard  to  separate  from  the  natural  growth  of  the  individual. 
The  sex  instincts  appear  in  full  vigor  only  as  the  individual 
approaches  maturity.  Other  instincts  come  in  part  at  least 
through  the  growth  of  the  nervous  system;  they  unfold 
one  by  one  as  the  corresponding  growth  takes  place.  Still, 
it  must  be  insisted  that  practice  plays  a  part  in  the  develop- 
ment of  many  instincts  in  man  as  it  does  in  the  pecking  of 
the  chick  mentioned  above.  Furthermore,  if  the  instinct 
is  not  used  when  it  makes  its  appearance,  there  is  some  evi- 
dence that  it  may  fall  into  disuse  and  fail  to  exhibit  itself 


236        FUNDAMENTALS   OF  PSYCHOLOGY 

later  when  occasion  arises.  Instinctive  movements  depend 
upon  learning  for  their  development,  take  on  much  of  their 
specific  form  through  practice,  and,  in  some  cases  at  least, 
disappear  unless  used. 

Imitation  and  Play.  —  Specific  instances  of  the  way  in 
which  instinct  and  learning  cooperate  can  be  well  illus- 
trated by  imitation  and  play,  often  spoken  of  as  instincts. 
As  a  matter  of  actual  observation  we  find  that  imitation 
in  the  life  of  man  and  the  higher  animals  is  very  important. 
However,  it  is  not  possible  to  say  that  imitation  is  an 
instinct.  The  variety  of  movements  involved  is  too  great 
to  bring  it  under  the  head  of  a  complicated  reflex,  and,  so 
far  as  one  may  regard  it  as  a  search  for  a  goal  determined 
by  the  pleasure  of  the  attainment  of  the  goal,  nothing  more 
is  needed  to  account  for  it  than  the  general  instinctive 
pleasure  of  social  approval.  Thus,  when  the  child  learns 
to  speak,  it  may  be  said  roughly  to  be  through  imitation, 
but  analysis  proves  that  the  child  has  an  instinct  to  make 
sounds  of  no  particular  character.  When  by  chance  these 
result  in  words,  the  parents  recognize  and  repeat,  and  give 
evidences  of  pleasure  that  lead  the  child  to  attempt  to  say 
them  again;  or  the  child  may  himself  be  vaguely  conscious 
of  the  similarity  of  the  sounds  he  makes  to  words  that  he 
has  heard  and  so  be  more  interested  in  them  than  in  the 
other  sounds.  In  any  case  it  is  the  instinctive  pleasure  in 
sounds  from  others  of  his  kind,  and  the  approval  they  give 
to  his  own  efforts,  that  lead  to  the  repetition  of  the  sound 
once  made.  Imitation  in  older  individuals  of  movements 
that  are  already  known  in  their  elements  can  also  be  traced 
to  similar  general  instincts. 

Play  as  Instinctive  Expression.  —  Play  also  is  an  expres- 
sion of  many  instincts  rather  than  of  a  single  one.  The 
tendency  to  play  can  be  looked  upon  as  a  result  of  the 


DEVELOPMENT  OF   INSTINCTS  237 

general  tendency  to  action,  to  motor  discharge.  The  char- 
acter of  the  discharge,  the  particular  form  of  play  indulged 
in,  is  determined  in  part  by  the  environment  and  by  the 
general  social  instincts,  and  in  part  by  a  host  of  particular 
instincts.  Thus,  playing  with  a  doll  is  partly  imitation  of 
the  mother,  partly  an  early  budding  of  the  maternal  instinct; 
the  hunting  and  fighting  plays,  the  constructive  plays,  all 
forms  of  rivalry  and  competition,  are  but  the  exhibition  of 
different  instincts  under  make-believe  conditions,  under 
circumstances  assumed  to  exist  for  the  sake  of  the  play. 
At  most,  play  is  no  single  instinct  but  the  expression  of  a 
host  of  instincts  under  the  pressure  of  a  general  tendency 
to  act.  It  is  an  outlet  for  a  reserve  of  energy  under  the 
effects  of  stimulation.  The  value  of  play  in  developing 
capacities  through  practice  in  advance  of  the  actual  neces- 
sity is  obvious. 

The  Origin  of  Instinct 

The  Rise  of  Instinct.  —  The  origin  of  instinct  is  pri- 
marily a  problem  for  the  biologist.  Instincts  are  nervous 
dispositions  that  have  been  developed  in  the  different 
species  and  are  then  inherited.  The  way  in  which  instincts 
might  arise  has  attracted  most  attention,  as  the  inheritance 
is  largely  taken  for  granted.  The  opposing  general  theories 
of  evolution  —  the  theory  of  acquired  characters  and  the 
theory  of  natural  selection  —  have  been  appUed  to  its 
explanation.  For  psychology  either  theory  suffices.  It 
would  be  easier  to  explain  instinct  as  the  inheritance  of  the 
tendency  to  make  movements  that  have  been  repeatedly 
made  by  the  ancestors,  but  a  great  many  biologists  are  at 
present  sceptical  of  the  possibility  of  such  an  inheritance 
(the  inheritance  of  acquired  characters),  and  psychology 
has  no  evidence  of  its  own  to  offer  in  its  favor.    It  is  certain 


238        FUNDAMENTALS   OF  PSYCHOLOGY 

that  no  specific  acts  which  have  been  developed  in  a  high 
degree  by  the  father  exhibit  themselves  in  the  child;  and 
when  any  particular  capacity  of  the  father  can  be  detected 
in  the  child,  it  is  doubtful  whether  it  is  not  due  to  the  inherit- 
ance of  the  father's  innate  characters,  rather  than  inherit- 
ance of  his  training.  Barring  inheritance  of  acquired  char- 
acters, instincts  must  be  due  to  the  selection  of  the  individ- 
uals who  chance  to  develop  tendencies  to  responses  favorable 
to  survival.  The  cause  of  the  change  in  the  germ  plasm  that 
produces  the  favorable  instinct  is  not  at  all  determined.  It 
may  be  due  to  some  chemical  action,  as  in  some  cases  it  has 
been  shown  to  be  induced  by  physical  stimuK;  but  given 
the  change,  however  it  arises,  it  tends  to  persist  in  the  later 
generations.  All  that  the  doctrine  of  natural  selection 
asserts  in  addition  is  that  those  organisms  which  chance 
to  develop  tendencies  to  action  favorable  to  their  survival 
and  to  the  continuance  of  the  species  will  increase  in  num- 
bers, and  those  which  fail  to  develop  this  tendency  will  die 
out  and  their  instincts  will  die  with  them.  As  a  result  of 
this  selection  in  the  course  of  the  ages  and  innumerable 
generations  of  individuals,  we  find  man  a  being  provided 
with  many  of  the  structures  essential  to  his  present  method 
of  living,  as  well  as  many  that  are  left  over  from  stages  in 
which  they  may  have  been  useful,  but  which  are  now  at 
best  not  harmful.  Similarly,  selection  has  given  a  nervous 
system  with  connections  and  predispositions  that  are  on 
the  whole  adequate  to  the  direction  of  the  bodily  structures, 
although  there  are  some,  those  at  the  basis  of  many  of  the 
fears,  for  example,  that  might  easily  be  dispensed  with. 

In  conclusion,  we  must  assume  that  a  number  of  the  most 
fundamental  reactions  and  demands  of  the  organism  are 
present  in  it  from  birth  and  serve  as  a  foundation  for  the 
superstructure  of  learning.    In  part  these  are  specific  acts 


DEVELOPMENT  OF   INSTINCTS  239 

or  groups  of  acts,  in  part  they  make  their  effect  felt  as  ends 
towards  which  the  organism  must  struggle  by  whatever 
movements  it  may  have  at  its  disposal.  There  seems  to 
be  a  possibility  of  making  either  the  movements  that  are 
aroused  through  instinct,  or  the  feeling  that  accompanies 
the  movement,  fundamental  in  the  explanation  of  all  in- 
stincts. In  the  one  case,  each  situation  would  call  out  a 
definite  response,  and,  where  the  obvious  response  was 
lacking,  it  could  be  assumed  that  it  was  still  present  in 
some  obscured  or  unnoticed  form.  On  the  other  hand,  it 
might  be  assumed  that  it  is  the  feeling  which  is  instinctive, 
—  the  pleasure  that  accompanies  the  instinctively  deter- 
mined proper  end,  and  the  unpleasantness  or  restlessness 
that  persists  until  that  end  is  attained.  As  has  been  seen, 
one  theory  would  hold  very  satisfactorily  for  one  type  of 
instinct,  the  other  just  as  satisfactorily  for  another.  It 
seems  more  in  harmony  with  the  facts  and,  on  the  whole, 
to  offer  less  difficulty  for  the  theory,  to  assume  that  both 
the  movement  and  the  feeUng  are  accompaniments  or  results 
of  the  single  biological  predisposition.  At  the  lower  level 
the  movement,  at  the  upper  levels  the  end  which  asserts 
itself  only  because  it  is  pleasant  when  attained,  are  the 
more  frequent  characteristics  of  the  instinct.  This  leaves 
much  to  be  explained,  but  it  does  permit  the  use  of  the  word 
in  the  broad  sense,  implied  if  not  exphcitly  adopted,  by 
modern  psychologists. 

In  instinct  we  find  the  source  of  most  of  the  movements 
and  many  of  the  feehngs  which  we  cannot  explain  by  imme- 
diate stimuli  or  from  the  earher  experience  of  the  individual. 
It  not  merely  provides  the  germ  which  is  later  developed 
into  the  compHcated  movements,  but  also  many  of  the 
strongest  incentives  that  we  have  in  connection  with  our 
most  complex  voluntary  and  rational  life.    If  one  ask  why 


240        FUNDAMENTALS  OF  PSYCHOLOGY 

one  is  afraid  of  the  dark,  why  the  mysterious  thrills,  the 
answer  can  be  given  only  in  terms  of  instinct.  Similarly, 
if  one  ask  why  acquiring  wealth,  or  inventing  a  new 
machine,  or  discovering  some  new  truth,  should  be  of  almost 
universal  appeal,  we  can  again  reply  only  that  they  are 
instincts.  If  one  seeks  the  reason  for  falling  in  love,  and  for 
many  of  the  actions,  particularly  of  the  thrills  and  blushings 
and  tones  peculiar  to  that  state,  one  must  look  to  instinct. 
Finally,  and  most  important  of  all,  the  social  instinct  sup- 
pHes  the  desire  to  be  popular,  to  seek  the  approval  of  com- 
panions, upon  which  depends  the  force  of  social  convention, 
and  which  drives  to  work  when  individual  need  and  indi- 
vidual instinct  exhaust  their  impelHng  power.  If  this 
extreme  statement  would  seem  to  make  everything  worth 
while  only  because  of  its  instinctive  appeal,  it  must  be 
remembered  that  instinct  is  developed,  modified,  and  even 
restrained  through  experience,  and  reduced  to  conventional 
type  by  social  pressure,  itself  an  expression  of  the  social 
instinct.  Certain  it  is  that  very  many  of  the  phenomena  in 
connection  with  feehng  and  action  and  particularly  in 
emotion  can  be  understood,  if  they  are  to  be  understood  at 
all,  only  through  instinct. 

REFERENCES 

McDougall:  Social  Psychology.  * 

Morgan:  Habit  and  Instinct. 

Watson:  Behaviour. 

Watson:  Psychology  from  the  Standpoint  of  a  Behaviorist. 

James:  Principles  of  Psychology,  Vol.  II,  Chap.  XXIV. 

Pillsbury:  Psychology  of  Nationality,  Chap.  II. 


CHAPTER  VIII 

RECALL,  AND    THE    QUALITIES    OF    RECALLED 
EXPERIENCES 

Not  all  of  the  material  of  knowledge  comes  directly  from 
the  sense  organs.  Memory,  imagination,  and  similar  pro- 
cesses have  an  equal  part  in  our  mental  Hfe.  From  the 
objective  point  of  view,  behavior  is  controlled  by  the  past 
as  well  as  by  the  present  stimuli.  Provisionally  we  may  re- 
call and  use  memories  as  if  they  were  on  the  same  level 
as  sensations.  We  may  think  of  them  as  composed  of 
definite  pictures  which  return  as  wholes  or  are  recom- 
pounded  of  elements  derived  from  the  senses.  We  must 
seek  to  determine  their  components,  and  to  discover  how 
they  are  retained,  and  the  laws  that  govern  their  reappear- 
ance. The  primary  quaHties  are  like  sensations.  No  abso- 
lutely new  quahties  can  be  imagined.  Speaking  generally, 
the  quaHties  of  memory  and  imagination  are  the  qualities 
of  sensation.  It  is  possible  to  go  farther  and  assert  that  if 
one  is  to  have  in  mind  images  of  a  given  quality,  one  must 
at  some  time  have  had  sensations  of  the  corresponding 
quality.  Individuals  blind  from  birth  cannot  imagine 
colors;  even  the  color  bhnd  cannot  picture  the  colors 
which  they  cannot  see.  The  same  holds  for  all  other  senses. 
This  has  led  to  the  general  acceptance  in  modern  times  of 
the  statement  that  all  images  are  derived  primarily  from 
sensations.  This  simpHfies  our  discussion  to  an  investiga- 
tion of  how  the  original  impressions  are  retained,  how  they 
may  be  rearoused  as  occasion  demands,  and  how  their 
quaHties  differ  from  those  of  the  original. 
241 


242        FUNDAMENTALS  OF  PSYCHOLOGY 

Retention 

The  Nature  of  Retention.  —  Before  asking  how  memories 
are  retained  we  must  inquire  where  they  are  retained.  Two 
possibihties  have  been  suggested  in  the  history  of  the 
science:  one  that  they  are  retained  in  mind  or  as  mental 
states,  the  other  that  they  are  held  in  the  nervous  system. 
The  latter  view  is  at  present  generally  accepted.  The 
theoretical  objection  to  thinking  of  memories  as  retained  in 
the  form  of  mental  states  is  that  mental  states  are  by  defini- 
tion conscious,  whereas  actually  there  is  no  awareness  of 
memories  until  they  are  revived.  The  individual  cannot 
tell  that  he  has  a  memory,  until  he  tests  it  by  trying  to  call 
up  particular  facts.  On  the  positive  side,  the  evidence 
that  remembering  is  in  some  way  dependent  upon  the  nerv- 
ous system  comes  from  pathology.  Numerous  cases  present 
themselves  in  which  loss  of  memory  is  one  of  the  prominent 
symptoms,  and  these  usually  show,  on  examination  of  the 
brain,  injuries  of  portions  of  the  cortex.  Destruction  of  the 
area  corresponding  to  a  sense  brings  with  it  loss  of  the 
corresponding  memories;  destruction  of  neighboring  areas 
or  of  paths  of  connection  with  other  portions  of  the  cortex 
also  destroys  or  impairs  the  effectiveness  of  recall  of  the 
images.  Studies  in  mental  pathology  have  convinced 
psychologists  that  memory  processes  are  closely  dependent 
upon  the  nervous  system. 

The  methods  of  retaining  memories  offer  more  room  for 
discussion.  Various  theories  have  been  suggested,  from 
the  crude  theory  of  the  Greeks  that  memories  were  im- 
printed on  the  brain  or  soul,  as  the  impression  of  the  seal 
upon  wax,  to  the  scarcely  less  crude  anatomical  theory  that 
each  idea  has  a  cell  in  the  brain  in  which  it  may  be  stored. 
At  present  the  tendency  is  to  find  analogies  that  shall  be 


RETENTION  243 

within  the  known  possibilities  of  the  nervous  system,  and 
not  to  make  the  explanation  more  specific  than  the  known 
facts  warrant.  The  explanation  is  usually  in  terms  of  func- 
tion, of  what  the  nervous  system  does  when  it  remembers, 
rather  than  of  the  manner  in  which  it  holds  the  memories. 
Hering  was  among  the  first  of  the  modern  writers  to  suggest 
this  method  of  approach,  in  stating  that  memory  is  a  univer- 
sal property  of  matter.  Any  change  that  may  be  suffered 
by  any  substance  tends  to  persist.  Garments  wrinkle  where 
they  have  been  often  creased;  for  example,  the  folding  is 
*  remembered '  by  the  garment.  Scars  on  the  skin,  even 
nail  holes  in  boards,  are  memories,  according  to  Hering, 
effects  left  on  the  substance  by  changes  it  has  undergone. 
In  the  organic  world  similar  facts  are  particularly  striking. 
The  physician  constantly  finds  that  any  injury  or  disease 
of  a  tissue  leaves  an  effect,  —  it  is  weakened  for  a  con- 
siderable time.  On  the  other  side,  exercise  of  a  muscle 
strengthens  it. 

Retention  and  Habit.  —  Habit  is  the  best  known  expres- 
sion of  this  fact  in  its  relation  to  the  nervous  system-.  As 
was  said  in  Chapter  VI,  habit  may  be  defined  in  its  most 
general  form  as  a  change  induced  in  a  tissue  as  a  result  of 
some  act.  This  leaves  a  tendency  to  do  that  same  thing 
more  easily.  Signs  of  habit  formation  may  be  seen  even  in 
the  unicellular  organisms.  A  Stentor  responds  differently 
after  a  series  of  responses  have  failed  to  give  a  pleasant 
result;  and  after  the  new  variation  has  been  repeated  sev- 
eral times,  it  tends  to  persist  for  some  time,  too,  — becomes 
a  habit.  In  the  higher  organisms  one  may  think  of  both 
habit  formation  and  of  memory  as  due  to  persistence  of 
changes  wrought  in  the  nervous  system  by  its  action. 
Habits  are  regarded  as  due  to  changes  in  the  synapses  of  the 
nervous  system.    Neurones  that  have  acted  together  once, 


244        FUNDAMENTALS   OF  PSYCHOLOGY 

tend  to  act  together  again;  nervous  impulses  spread  from 
tlie  one  first  active  to  the  others,  owing  to  the  lessened 
resistance  of  the  synapses  that  intervene.  From  the  stand- 
point of  Hering,  memory  in  its  essentials  has  the  same  basis. 
It  is  primarily  the  capacity  of  retaining  the  effects  of  one 
action  of  the  nervous  system  in  a  form  that  shall  make 
probable  its  repetition  at  some  time  in  the  future,  rather 
than  the  retaining  of  some  static  thing,  or  impression,  or 
idea.  Speaking  generally,  after  an  object  has  once  been 
perceived,  a  tendency  persists  for  the  neurones  involved  to 
act  in  the  same  way  again,  and  this  tendency  leads  to  the 
revival  of  the  image  on  suitable  occasions.  The  nervous 
system  may  be  regarded  as  acting  in  a  certain  way  at  the 
time  of  perception,  and  of  repeating  approximately  the  same 
action  at  some  later  time.  Those  portions  of  the  cortex 
which  are  concerned,  become  connected  as  a  unitary  whole, 
and  when  one  part  is  reexcited,  the  others  are  rearoused. 
What  is  left  is  merely  the  physical  or  chemical  change  in 
the  neurones.  Where  this  change  takes  place,  can  be  deter- 
mined only  by  indirect  means.  Present  evidence  makes  it 
probable  that  the  most  important  part  of  the  change  is 
found  in  the  sensory  areas  or  in  the  immediately  adjoining 
association  areas,  although  no  portion  of  the  original 
nervous  tract  can  be  absolutely  excluded  from  considera- 
tion. 

After-image,  Memory  After-image,  and  Memory  Image. 
—  One  may  also  trace  an  analogy  between  memory  and 
simpler  forms  of  retention  or  prolongation  of  activity  in 
the  sense  organ.  In  vision,  gradations  may  be  traced  be- 
tween the  after-image  and  the  memory  image.  If  one  look 
for  a  moment  at  a  bright  color,  the  sensation  will  probably 
last  for  a  fraction  of  a  second  after  the  impression  has  been 
removed.    Even  faint  objects  leave  a  second  image,  clearer 


RETENTION 


245 


and  of  longer  duration  than  the  first,  which  does  not  move 
with  the  eyes,  and  may  be  shown  to  have  its  seat  in  the  cor- 
tex. This  process  is  known  as  the  primary  memory,  and  is 
probably  partly  identical  with  what  Fechner  called  the 
memory  after-image.  It  is  sufficiently  distinct  to  be  used 
for  all  purposes  in  place  of  the  actual  sensation,  and  is  for 
many  purposes  even  more  effective  than  the  sensation.  It 
may  be  regarded  as  due  to  a  persistence  of  the  activity  of 
the  cortical  elements  involved  in  sensation  in  just  the  same 
way  that  the  after-image  is  a  continuation  of  the  action  of 
the  retinal  elements.  The  cortical  cells  have  even  greater 
inertia  and  so  act  for  a  longer  time  than  the  rods  and  cones. 
A  memory,  on  the  same  analogy,  is  merely  the  reinstate- 
ment of  the  primary  memory  image  after  the  lapse  of  a 
longer  or  shorter  period.  The  same  nervous  elements 
may  be  assumed  to  be  active  at  the  moment  of  recall  as  in 
the  original  stimulation,  but  they  cease  to  act  or  at  least 
cease  to  produce  conscious  processes  for  a  longer  or  shorter 
time,  and  then  the  activity  is  in  some  way  reinstated.  The 
three  —  after-image,  memory  after-image,  and  memory 
image  —  all  exhibit  many  of  the  same  laws,  and  may  be 
regarded  as  succeeding  steps  in  the  same  series.  The  after- 
image is  the  persistence  of  the  effect  in  the  sense  organ; 
the  primary  memory,  a  persistence  of  the  activity  of  cells 
in  the  cortex;  memory,  a  reinstatement  of  the  activity  in 
the  cells  of  the  cortex  involved  in  the  primary  memory. 

Perseveration.  —  Granted  the  existence  of  a  tendency  to 
act  again  in  a  way  once  acted,  it  is  next  in  order  to  ask  how 
or  when  this  reinstatement  of  the  activity  may  take  place. 
Two  occasions  are  ordinarily  recognized  at  present,  —  the 
perseverative  tendency,  and  association.  The  former  is 
simpler,  although  less  frequent  and  less  generally  accepted. 
It  was  suggested  by  Miiller  and  Pilzecker  that,  when  an 


246        FUNDAMENTALS  OF  PSYCHOLOGY 

impression  has  been  made,  the  nerve  cells  impressed  con- 
tinue active  for  a  time,  and  in  consequence,  the  correspond- 
ing ideas  are  likely  to  force  their  way  into  consciousness 
when  nothing  else  offers,  or  to  combine  with  other  processes 
active  at  the  same  time  in  the  production  of  more  complex 
processes.  This  they  call  perseveration.  Instances  men- 
tioned are  the  reappearance  of  words  that  have  been  heard 
or  spoken  just  before,  but  have  no  noticeable  connection 
with  the  course  of  thought;  the  tendency  of  tunes  to  'run 
in  the  head';  of  complicated  practical  problems  to  keep 
returning  to  mind  on  all  occasions,  etc.  This  tendency 
seems  to  decrease  rather  quickly  at  first,  but  some  sUght 
effect  apparently  persists  for  hours,  and  when  the  original 
event  is  interesting  or  the  impression  strong,  may  last  for 
several  days.  It  is  assumed  that  the  activity  of  the  nerve 
cells  is  continuous,  but  that  the  effect  of  their  activity  rises 
to  consciousness  only  now  and  again.  While  the  persevera- 
tion tendency  itself  is  unquestioned,  it  is  a  matter  of  dispute 
how  long  it  continues  and  whether  the  reappearance  of  the 
experiences  after  a  little  time  are  due  to  it,  or  to  associations 
that  have  not  been  noticed. 

Association 

Laws  of  Association.  —  Association  as  an. explanation  of 
recall  can  be  traced  back  to  Aristotle  in  fairly  accurate  for- 
mulation, and  approximations  to  it  are  found  in  still  earUer 
writers.'    In  one  or  another  form  it  is  recognized  by  all.    In 

1  Closely  related  in  meaning  to  association  is  the  word  suggestion.  Sug- 
gestion, too,  is  used  to  designate  the  recall  of  one  idea  by  another.  Since, 
however,  suggestion  is  also  used  for  the  evocation  of  a  movement  by  an 
idea,  and  particularly  because  it  has  been  applied  very  generally  to  the 
arousal  of  ideas  and  movements  in  hypnotism  and  similar  more  or  less 
abnormal  conditions,  the  psychologist  usually  avoids  the  use  of  the  term  in 
connection  with  the  normal  processes. 


ASSOCIATION  247 

general,  this  doctrine  asserts  that  all  reproduction  of  ideas 
is  determined  by  the  connections  that  have  been  formed 
at  some  time  in  the  past.  Conversely,  mental  processes 
which  have  once  been  in  consciousness  together,  tend  to 
return  together.  An  empirical  study  of  learning  shows 
that  words,  nonsense  syllables,  or  objects  shown  together 
or  in  immediate  succession,  tend  to  become  connected  and, 
when  one  is  presented  again,  the  other  may  also  reappear. 
Learning  the  name  of  a  new  object,  connecting  a  person 
with  a  place  where  he  has  been  seen,  all  rote  learning,  are 
instances  of  this  fact.  On  the  physiological  side,  it  may  be 
said  that  all  learning,  all  experience,  is  of  things  in  their 
connections,  and  that  all  return  is  through  the  connections 
formed  between  neurones  at  the  instant  of  learning.  When 
a  group  of  neurones  is  active  at  the  time  of  the  original 
experience,  paths  of  connection  are  formed,  synapses  are 
opened  between  them,  and,  later,  when  any  element  of  the 
complex  is  aroused  in  any  way,  the  impulse  tends  to  spread 
over  the  partially  open  synapses  to  the  other  elements  of 
the  whole.  Association  has  the  same  basis  as  habit,  but 
need  not  end  in  a  muscular  response.  As  was  said  in  the 
beginning  of  the  chapter,  all  learning  is  like  habit  formation; 
all  learning  is  dependent  upon  formation  of  connections 
between  neurones,  —  nothing  can  be  learned  in  isolation. 
In  consequence,  association  is  at  once  the  fundamental 
fact  in  learning,  in  retention,  and  in  recall.  Learning  is 
always  the  formation  of  connections  between  neurones; 
retention  is  always  the  persistence  of  the  connection,  or 
the  partial  openness  of  synapses  which  permits  an  impres- 
sion to  pass  from  one  to  the  other  of  the  connected  elements; 
recall  is  the  rearousal  of  the  whole  complex  by  some  one 
of  the  elements  that  may  be  stimulated  from  the  outside 
world,  directly  or  indirectly. 


248        FUNDAMENTALS  OF  PSYCHOLOGY 

While  from  the  standpoint  of  learning  it  may  be  asserted 
with  assurance  that  impressions  presented  together  tend 
to  return  together,  more  complication  appears  when  one 
attempts  to  determine  what  it  is  that  brings  any  particular 
old  experience  to  mind.  Any  idea  that  returns  has  almost 
always  been  associated  with  several,  often  with  many, 
experiences;  and  it  is  difficult  to  say  which  one  has  been 
responsible  for  its  recall.  In  fact,  a  number  of  factors  more 
or  less  remote  usually  cooperate  in  the  recall.  Similarly,  if 
some  one  famihar  experience  be  presented,  it  is  not  possible 
to  say  with  certainty  what  idea  will  be  recalled  by  it.  One 
may  study  the  tendencies  to  recall,  by  presenting  a  number 
of  words  to  a  subject,  and  letting  him  speak  the  first  word 
that  comes  to  mind.  If  the  same  list  of  words  be  presented 
to  a  number  of  persons  of  approximately  the  same  earlier 
experience,  it  is  found^that  a  large  number  of  the  responses 
will  be  common  to  all/  Kent  and  Rosanof!  secured  the  asso- 
ciations called  out  in  a  thousand  people  to  each  of  one  hun- 
dred words  and  found  that  the  number  of  common  words 
was  very  large.  Thus  to  man,  394  responded  woman,  99 
male,  30  strength,  44  hoy,  30  person,  etc.;  to  mountain,  246 
responded  high,  184  hill,  73  height,  90  valley;  to  soft,  365 
responded  hard,  53  pillow,  34  easy,  etc.  If  one  will  permit 
the  train  of  ideas  to  wander  uncontrolled  for  five  seconds 
and  then  write  down  the  ideas  that  present  themselves, 
similar  connections  can  be  traced.  The  connections  have 
from  time  immemorial  been  classified  under  four  heads,  — 
contiguity,  succession,  similarity,  and  contrast.  In  our 
list  of  words  it  will  be  seen  that  all  the  connections  given 
can  be  traced  to  one  of  these  groups.  Soft  and  hard,  moun- 
tain and  valley,  man  and  woman,  may  be  regarded  as  con- 
trasting; hill  and  mountain,  soft  and  easy,  man  and  male, 
may  be  regarded  as  similar;    soft  and  pillow,  high  and 


ASSOCIATION  249 

mountain,  man  and  strength,  as  connected  through  verbal 
succession  or  by  contiguity  of  the  objects. 

It  should  be  noted  that  this  is  a  classification  of  the  con- 
nections after  they  have  been  formed,  and  is  made  after 
rather  than  before  the  fact.  It  is  a  classification  of  the  rela- 
tion the  ideas  hold  to  each  other,  rather  than  a  statement 
of  the  causes  of  recall.  Even  so  far  as  it  holds,  it  is  not 
altogether  unambiguous.  Mountain  and  valley  are  con- 
tiguous as  well  as  contrasting,  man  and  woman,  as  all 
contrasting  things  must  be,  are  in  some  degree  similar;  they 
also  are  frequently  found  together  and  the  words  have  been 
repeated  in  succession.  For  the  real  cause  of  arousal,  we 
must  turn  again  to  the  neurones  that  are  involved  in  the 
activity. 

The  Nervous  Basis  of  Association.  —  A  new  method  of 
forming  connections  in  the  nervous  system  seems  to  be 
impHed  in  the  association  process.  Hitherto,  all  of  the 
connections  studied  have  run  from  the  sensory  to  the  motor 
neurones;  and  the  synapses  that  open  are  those  that  are 
traversed  by  the  impulse.  In  association  the  connection 
is  formed  between  two  groups  of  sensory  neurones  and  be- 
tween groups  of  neurones  not  on  a  single  sensori-motor  arc. 
Thus  when  a  child  is  shown  an  object  and  hears  the  name 
spoken,  the  sight  of  the  object  excites  a  region  in  the  occipi- 
tal lobe;  the  name  heard  arouses  the  auditory  area  in  the 
temporal  lobe.  These  areas  are  widely  separated  on  the 
cortex,  yet  nevertheless  after  frequent  recurrence  of  the 
excitations,  a  connection  is  formed  between  them  of  such 
a  character  that  when  the  object  is  seen  the  name  is  thought, 
and  when  the  name  is  heard  the  image  of  the  object  is 
reinstated.  Two  theories  have  been  held  to  explain  the 
way  in  which  the  path  is  formed.  One  is  that  the  path  is 
estabhshed  indirectly  through  some  common  pathway  of 


250        FUNDAMENTALS   OF  PSYCHOLOGY 

motor  discharge.  It  is  impKed  that  the  sound  heard  would 
lead  to  an  attempt  to  repeat  it,  and  the  object  seen  would 
lead  to  the  same  response,  and  that  all  that  would  be  needed 
would  be  to  cross-connect  the  two  sensory  areas.  This,  it 
might  be  argued,  again  could  be  established  indirectly  by 
a  backward  opening  of  the  path  from  the  motor  response  to 
the  sensory  stimulus  not  previously  evoking  it. 

Association  as  Conditioned  Reflex.  —  This  form  of  asso- 
ciation is  what  Watson  has  called  the  conditioned  reflex  on 
the  motor  side.  It  is  well  typified  in  the  dog  which  produces 
a  salivary  secretion,  —  ordinarily  induced  by  the  sight  of 
food,  —  in  response  to  the  sound  of  a  bell  that  has  been 
frequently  sounded  at  the  same  time  that  the  food  is  seen. 
Similarly  when  a  child  is  shown  a  cat  at  a  time  when  it  is 
indifferent  to  cats  and  at  the  same  time  a  bell  is  sounded 
loudly  enough  to  startle  it,  the  withdrawal  that  comes 
with  the  bell  is  gradually  transferred  to  the  cat.  Three 
objections  may  be  raised  to  the  assumption  that  the 
motor  response  is  at  all  necessary  to  the  formation  of  the 
connection.  In  the  first  place,  the  two  motor  discharges 
ordinarily  run  towards  the  same  outlet,  but  with  no  lines 
of  communication  between  them.  In  the  second  place,  to 
assume  that  the  path  is  formed  along  the  lines  of  motor 
discharge  means  that  the  impulse  runs  fronEi  motor  to  sen- 
sory neurones.  In  the  third  place,  connections  of  this  cross 
character  are  formed  when  no  noticeable  movement  results. 
These  considerations  make  it  necessary  to  assume  that  both 
for  motor  cross  connections  and  sensory  associations  direct 
paths  must  be  opened  by  the  simultaneous  activity  of  parts 
of  the  nervous  system. 

The  Law  of  Drainage.  —  The  general  assumption  is  that 
any  two  regions  active  at  the  same  time  either  as  parts  of 
two  sensory  excitations  or  of  two  sensori-motor  pathways 


ASSOCIATION  251 

tend  to  have  paths  opened  between  them.  This  is  what 
McDougall  called  the  'law  of  drainage,'  for  he  argued  that 
whenever  two  parts  of  the  cortex  are  active  at  the  same 
time  or  in  immediate  succession  the  neural  excitation  of 
one  tends  to  drain  over  into  the  other.  This  term  'drainage' 
is  perhaps  an  inadequate  picture,  as  the  nervous  discharge 
is  very  sudden,  although  there  is  the  long-drawn-out-after 
effect  of  perseveration,  during  which  something  like  drain- 
age may  go  on.  However  it  be  imaged,  there  can  be  no 
doubt  of  the  fact  that  simultaneous  activity  of  two  parts 
of  the  cortex  opens  a  path  between  them  of  such  a  character 
that  whenever  the  one  is  aroused  at  a  later  time  the  other 
also  tends  to  be  aroused.  The  more  frequent  the  repetition 
of  this  common  excitation,  particularly  when  the  excitation 
later  spreads  by  association  from  one  to  the  other,  the 
stronger  is  the  tendency  for  one  to  arouse  the  other. 

One  fact  that  limits  the  generaUty  of  this  statement  is 
that  not  all  elements  that  are  active  simultaneously  become 
so  closely  connected  that  one  actually  will  recall  the  other. 
Only  those  elements  which  for  some  reason  have  something 
in  common  seem  to  be  firmly  united.  Those  that  are  at- 
tended to  together,  those  which  lead  to  a  single  act,  those 
which  are  particularly  intense  or  are  accompanied  by  a 
strong  emotion  are  strongly  associated.  Of  these  cases,  the 
only  one  that  would  give  any  evidence  of  the  occasion  for 
selecting  one  element  rather  than  another  in  forming  an 
association  is  that  they  lead  to  a  common  act.  This  as 
stated  above  is  not  really  a  cause,  since  they  lead  to  the 
common  act  as  a  result  of  their  association,  rather  than 
becoming  united  because  they  both  excite  the  same  move- 
ment. At  present  then  we  can  go  no  farther  in  our  explana- 
tion of  how  these  neurones  become  associated  than  to 
assert  that  when  two  groups  of  neurones  in  any  part  of  the 


252        FUNDAMENTALS   OF  PSYCHOLOGY 

cortex  are  strongly  excited  at  the  same  time  or  in  close 
succession,  a  path  is  opened  between  them,  and  thereafter 
whenever  one  is  excited  the  other  tends  to  be  excited  also. 

Physiological  Classification  of  Association.  —  The  cause 
of  the  permeability  of  the  synapses  may  be  made  the  corre- 
late of  either  contiguity  or  of  succession.  The  former  is 
the  simpler,  as  it  is  an  expression  of  the  law  that  two  ele- 
ments active  together  once,  tend  to  act  together  from  that 
time  on.  Succession  has  practically  the  same  explanation. 
The  second  neurone  begins  to  act  before  the  first  ceases  its 
activity,  and  so  the  two  actions  of  the  neurones  are  simul- 
taneous. If  similarity  is  to  be  explained  in  physiological 
terms,  it  must  be  reduced  to  partial  identity.  What  one 
calls  an  idea  is  always  complex  and  may  be  pictured  as 
corresponding  to  the  action  of  a  number  of  neurones.  In 
what  is  classified  as  association  by  similarity,  a  mass  of 
neurones  corresponding  to  the  first  idea  are  active,  and  as 
time  goes  on,  parts  of  the  group  cease  to  be  active.  Only 
the  one  group  that  corresponds  to  the  part  of  the  idea  most 
attended  to  at  the  moment  persists  in  its  activity;  and 
from  this,  new  neurones  that  correspond  to  the  elements 
of  the  second  idea  are  excited  by  virtue  of  their  previous 
connections  with  the  persisting  portions  of  the  first.  On 
the  side  of  consciousness,  many  'ideas'  in  the  popular  use 
of  the  term  are  complexes  of  experiences,  complexes  of 
sensations;  probably  also  the  action  of  many  different 
neurones  is  involved  in  their  appearance.  In  the  recall  of 
any  complex  idea,  these  different  elements  probably  enter 
into  many  different  combinations,  and  the  effective  con- 
nections are  between  the  elements,  not  between  the  larger 
masses.  Thus  when  an  idea  recalls  another  similar  one,  the 
similarity  is  due  to  some  common  element,  and  this  common 
element  may  be  regarded  as  persisting  from  one  idea  to  the 


ASSOCIATION  253 

other.  In  one  idea,  everything  disappears  except  the  ele- 
ments that  are  common;  these  persist  and  gather  about 
them  by  association  the  other  elements  which  with  them 
may  be  regarded  as  constituting  the  new  idea.  When  the 
ideas  are  classified  afterwards,  they  are  seen  to  be  similar, 
the  association  is  said  to  be  by  similarity,  but  the  effective 
forces  have  been  the  waning  of  certain  elements  of  the  first 
idea  and  the  excitation  of  others  by  those  remaining.  Asso- 
ciation by  similarity  is  really  through  partial  identity,  and 
the  identical  element  furnishes  the  bond  of  connection. 

The  Limits  of  Association.  —  Not  only  must  we  limit 
the  appHcation  of  the  doctrine  of  associations  by  the  asser- 
tion that  it  is  the  neurones  at  the  basis  of  the  elements  of 
ideas  that  are  associated  rather  than  the  ideas  themselves, 
but  we  must  also  recognize  that  associations  give  only  the 
possibihty  of  recall,  and  that  selection  from  the  possible 
associates  must  be  made  by  more  remote  factors.  Most 
neurones  or  sensory  elements  have  been  connected  at  differ- 
ent times  with  several  other  elements,  and  may  be  regarded 
as  having  a  tendency,  whenever  any  one  is  aroused  in  any 
way,  to  rearouse  each  of  the  others  with  which  it  has  been 
connected.  Which  of  the  possible  elements  shall  be  aroused 
is  determined  by  the  same  elements  that  control  attention. 
A  discussion  of  these  may  be  postponed  to  the  next  chapter. 
For  the  present  we  may  say  that  the  return  of  an  experience 
or  the  renewal  of  an  excitation  of  a  group  of  neurones 
depends  in  some  degree  upon  the  continued  activity  (per- 
severation) of  the  elements  in  question,  an  activity  that 
lasts  for  a  relatively  short  time,  but  for  the  most  part 
depends  upon  the  fact  that  when  any  two  groups  of  nerve 
cells  have  been  active  together  at  any  time  and  one  is 
reexcited,  that  excitation  tends  to  rearouse  its  earlier 
associates. 


254         FUNDAMENTALS   OF  PSYCHOLOGY 

Images,  or  Centrally  Aroused  Sensations 

The  Qualities  of  Centrally  Aroused  Sensations.  —  These 
memory  processes  may  be  studied,  not  merely  to  deter- 
mine the  ways  in  which  they  are  retained  and  the  laws  of 
their  revival,  but  also  with  reference  to  the  actual  content 
that  they  offer.  One  may  study  the  materials  of  the  remem- 
bered impressions  just  as  one  may  study  the  qualities  that 
are  derived  from  the  external  senses  to  determine  the  ele- 
ments that  make  them  up  or,  more  profitably,  to  com- 
pare them  with  the  qualities  of  the  immediate  sensa- 
tions. 

Most  untrained  individuals  do  not  notice  the  content  of 
their  minds  as  they  recall;  they  are  content  to  know  that 
they  recall  an  object  and  can  describe  it.  Others  who  have 
had  training  in  introspection  find  that  they  do  not  have 
images;  they  have  no  definite  mental  content  when  they 
recall  an  object  but  have  merely  the  certainty  that  they 
have  seen  it  before.  Our  present  problem  is  to  determine 
what  is  in  mind  when  the  object  is  recalled.  If  one  is 
attempting  to  recall  a  desert  or  a  mountain  landscape  seen 
years  ago,  for  example,  one  may  either  repeat  words  that 
have  been  associated  with  the  experience  without  any 
definite  picture  of  the  landscape,  one  may  have  fleeting  bits 
of  yellow  sand  or  snow-covered  peaks  with  many  vacant 
areas  or  dark  gray  regions  with  no  definite  pictures,  or  one 
may  have  a  clear  and  distinct  picture  from  which  one  may 
paint  or  describe  many  if  not  all  of  the  details.  Our  ques- 
tion at  present  is  how  these  images  differ  from  individual 
to  individual,  and  how  they  resemble,  and  how  they  differ 
from,  actual  sensations. 

Two  methods  of  investigation  have  been  applied  to  the 
solution  of  this  problem.    The  first  of  these  was  used  by 


CENTRALLY  AROUSED   SENSATIONS       255 

Kiilpei  in  an  experiment  to  determine  how  one  might  dis- 
tinguish faint  sensations  from  imagined  or  remembered 
experiences.  Faint  sensations  were  chosen  because  mem- 
ories are  generally  beUeved  to  be  fainter  than  sensa- 
tions. Investigators  were  placed  in  a  dark  room  where 
faint  lights  of  different  colors  could  be  thrown  upon  the 
wall.  At  a  given  signal,  the  observers  were  asked  to  say 
whether  a  light  was  seen  and  then,  if  it  were  seen,  to  say 
whether  it  was  objective  or  merely  imagined.  At  times  a 
light  was  really  shown,  at  others  not.  In  most  cases  at  the 
signal  the  observers  either  saw  or  imagined  a  color.  After 
the  report  had  been  given,  an  attempt  was  made  to  deter- 
mine what  differences  were  used  as  a  basis  of  deciding 
whether  the  image  was  really  seen  or  only  imagined.  In 
this,  observers  varied.  All  agreed  that  there  was  a  constant 
difference  in  quality.  The  imagined  colors  were  more 
transparent,  were  net-Uke  or  clouded.  The  sensations 
seemed  brighter,  they  entered  and  left  consciousness  sud- 
denly and  as  wholes,  had  a  more  definite  form,  were  clearer, 
and  were  given  a  more  definite  position  in  space.  They 
were  distinguished  also  by  the  more  active  tests,  —  that 
sensory  colors  left  an  after-image,  were  stationary  when 
the  eyes  moved  and  vanished  on  closing  the  eyes,  —  while 
the  reverse  held  in  each  particular  for  the  imagined  pro- 
cesses. In  addition  there  were  individual  pecuUarities  from 
man  to  man;  for  example,  greater  duration  was  given  by  one 
as  characteristic  of  sensation  and  by  another  as  character- 
istic of  the  image.  The  results  of  this  investigation  indicate 
that  characteristically  different  qualities  attach  to  the  pro- 
cesses aroused  through  association  which  distinguishes  them 
from  the  real  sensations. 

The  Projection  of  the  Memory   Image.  —  Another  in- 

1  Kiilpe,  Philosophische  Studien,  vol.  19,  pp.  508-556. 


256        FUNDAMENTALS   OF  PSYCHOLOGY 

vestigation  gives  approximately  the  same  results  by  a 
method  even  more  striking.  Miss  Martin^  found  that  it 
was  possible  after  a  Httle  practice  to  project  a  memory 
image  outward  into  space,  where  it  might  be  more  readily 
compared  with  sensations.  The  different  location  of  images 
and  sensations  serves  in  our  ordinary  experience  as  one 
criterion  for  distinguishing  them.  We  refer  perceptions 
to  the  point  where  the  object  is  assumed  to  be  in  the  outside 
world,  while  the  memory  or  imagination  either  is  given  an 
indefinite  place,  is  projected  backward  within  the  head, 
or  possibly  referred  to  the  place  where  it  actually  is,  but 
usually  is  not  seen  upon  the  surface  that  is  actually  pre- 
sented to  the  eyes.  Miss  Martin's  observers  found  it  pos- 
sible to  bring  the  image  and  the  object  side  by  side.  When 
the  difference  in  projection  that  ordinarily  exists  between 
images  and  perceptions  had  thus  been  removed,  it  was 
found  that  there  were  still  characteristic  differences  between 
the  two  in  their  coloring,  in  definiteness  of  contours,  in 
clearness,  intensity,  and  stability.  The  sensations  had  the 
advantage  in  each  of  these  respects.  One  other  character- 
istic is  the  relation  to  the  movements  of  the  eyes.  While  in 
these  experiments  the  images  did  not  always  move  with  the 
eyes,  there  was  always  a  tendency  to  movement  when  the 
eyes  moved  that  could  be  avoided  only  by  considerable 
strain.  All  of  these  criteria  for  distinguishing  between  the 
two  agree  with  those  indicated  by  Kulpe's  investigation. 
One  other  presents  itself  for  certain  observers,  —  that  is,  the 
tendency  to  see  the  images  in  front  of  the  background  of 
sensory  objects  which  may  be  present.  The  background 
may  be  seen  through  them  as  through  a  veil.  In  general 
it  is  noticed  that  sensory  impressions  interfere  with  the 

1  Martin,  Die  Projektionsmethode  unci  die  Lolcalisation  visueller  und 
anderer  Vorstellungsbilder. 


CENTRALLY  AROUSED   SENSATIONS       257 

perception  of  other  objects,  while  images  do  not  thus  inter- 
fere. 

Individuals  who  possess  definite  images,  then,  have  also 
characteristic  means  of  distinguishing  them  from  the 
sensations.  The  images  are  sufficiently  different  from  the 
sensory  experiences  to  prevent  one  from  being  mistaken 
for  the  other.  Individuals  frequently  fail  to  notice  the 
characteristics  that  serve  to  distinguish  images  from  sensa- 
tions. In  fact,  few  make  this  distinction  until  it  has  been 
called  to  their  attention ;  but  the  differences  serve  to  ascribe 
the  process  to  the  world  of  things  if  of  one  character,  or  to 
the  world  of  memory  and  imagination  if  of  another  char- 
acter. In  addition  to  these  differences  in  the  mental  con- 
tent, the  connections  in  which  the  experiences  present 
themselves  also  play  a  part  in  determining  whether  an 
experience  is  objective  or  subjective.  If  the  object  or  event 
follows  naturally  upon  other  events  that  are  recognized  as 
objective,  if  the  sound  of  steps  is  heard  outside,  the  bell 
rings,  a  servant  answers,  and  a  moment  later  a  friend  enters 
the  room,  there  is  no  question  of  the  objectivity  of  the 
experience.  If,  on  the  other  hand,  a  letter  in  a  familiar 
handwriting  is  seen  and  then  an  image  of  the  friend  who 
wrote  the  letter  appears,  there  is  no  doubt  that  the  image 
is  subjective.  One  event  fits  into  the  world  of  things,  the 
other  into  the  world  of  memories,  and  in  consequence  the 
one  is  assigned  to  the  one  group,  the  other  to  the  other. 
This  placing  of  the  mental  process  in  terms  of  antecedent 
events  and  the  setting  is  undoubtedly  the  most  important 
of  the  factors  that  lead  us  to  discriminate  between  the 
objective  and  the  subjective.  Again  this  operation  is  not 
noticed  for  itself.  One  knows  at  once  that  one  sees  an  object 
in  the  one  case  and  that  one  merely  remembers  it  in  the 
other.     The  method  of  remembering  is  no  more  noticed 


258        FUNDAMENTALS   OF  PSYCHOLOGY 

than  is  the  method  of  perceiving.  That  it  is  necessary  to 
make  the  distinction  is  seen  from  the  fact  that  in  halluci- 
nations and  in  dreams  mistakes  are  made.  The  processes 
aroused  by  association  alone  are  referred  to  the  real  world 
and  are  treated  as  objects. 

Imagery  Types 

The  Materials  of  Memory  and  Imagination.  —  One  may 

in  a  degree  and  for  most  individuals  parallel  the  sensations 
which  are  regarded  as  constituting  the  raw  material  of  our 
external  experiences  by  a  series  of  images  or  centrally 
aroused  sensations  which  constitute  the  materials  out  of 
which  the  things  that  appear  in  memory,  imagination,  and 
reason,  are  composed,  'the  stuff  of  which  dreams  are  made.' 
These  are  retained  in  the  central  nervous  system  and  re- 
aroused  by  stimuli  that  have  been  connected  with  them  in 
the  past  and  by  other  ideas  that  have  been  experienced  with 
them.  It  should  be  noted  that  the  memory  images  are 
usually  not  so  complete  as  the  sense  presentations,  that 
even  the  clearest  of  them  have  large  gaps  due  either  to  im- 
perfect attention  at  the  time  of  perception  or  to  lack  of 
interest  in  some  phase  at  the  moment  of  recall.  Also  much 
of  our  memory  and  thinking  is  not  in  definite  reproductions 
or  constructions  of  the  objects,  but  is  very  sketchy.  It  is 
very  frequently  in  words  or  in  some  other  symbol  that 
represents  or  means  the  thing  rather  than  a  reinstatement  of 
the  elements  which  actually  constitute  it.  This  must  be 
considered  in  detail  later  on ;  it  is  mentioned  now  merely  as 
indicating  that  our  inner  mental  Ufe  is  not  to  be  described 
completely  in  terms  of  definite  images.  Even  where  cen- 
trally aroused  sensations  are  most  definite,  the  number  of 
quaHties  is  less  than  the  number  that  may  be  found  in 
immediate  sensation.     Of  the  hundreds  of  grays,  the  un- 


MEMORY  TYPES  259 

practised  man  cannot  recall  more  than  a  dozen.  Relatively 
few  elements  in  memory  must  be  made  to  do  duty  for  the 
vast  number  of  sensation  qualities. 

Memory  Types.  —  In  our  discussion  of  the  qualities  of 
the  centrally  aroused  processes,  it  must  be  noticed  not  only 
that  the  quahty  of  the  memory  element  is  not  the  same  as 
the  quahty  of  the  thing  represented,  but  the  way  in  which 
anything  is  recalled  differs  greatly  from  individual  to  indi- 
vidual. We  all  think  of  the  same  things,  but  probably  no 
two  of  us  have  in  mind  exactly  the  same  images  when  we 
think  of  the  object.  The  main  differences  in  representing 
objects  and  events  can  be  most  readily  stated  in  terms  of 
the  sense  organ  or  the  sense  material  that  is  emphasized 
or  drawn  upon  by  the  individual.  The  students  of  mental 
disturbance,  Charcot  among  the  first,  noticed  that  certain 
men  would  make  predominant  use  of  the  visual  memories, 
others  of  the  motor,  others  again  of  the  auditory.  Still 
later  Gal  ton  ^  made  a  careful  examination  of  the  way  a 
number  of  individuals  recalled  the  breakfast  table,  with 
the  result  that  some  were  found  who  would  merely  recall 
the  way  the  dishes  and  the  people  at  the  table  looked, 
others  could  remember  the  sounds  of  words  and  the  rattle 
of  the  utensils,  still  others  could  remember  only  how  their 
own  various  movements  felt  as  they  were  made.  More 
rare  were  the  individuals  who  could  remember  the  odors 
and  tastes  of  the  food,  and  these  memories  were  usually 
indistinct  and  subordinate.  Galton  also  distinguished  the 
verbal  type,  individuals  who  recalled  everything  in  words, 
either  as  words  seen,  or  words  heard,  or  words  as  they 
would  be  felt  in  the  vocal  organs  at  the  time  they  were 
uttered.  In  older  individuals,  particularly  men  of  science 
and  others  who  indulged  much  in  abstract  thought,  the 
^  Galton,  Inquiries  into  Human  Faculties. 


26o        FUNDAMENTALS   OF  PSYCHOLOGY 

verbal  tended  to  predominate  over  the  more  concrete 
imagery. 

Galton  or  certain  of  his  expositors  give  the  impression 
that  an  individual  is  Hkely  to  have  one  type  to  the  exclu- 
sion or  at  the  expense  of  all  others.  Certain  of  the  later 
writers  have  still  more  exaggerated  this  assertion  of  the 
mutual  exclusiveness  of  types.  Strieker,  for  instance,  has 
argued  that  every  one  must  be  of  the  motor  type,  and  fur- 
ther that  the  recall  consists  in  nothing  more  than  the  rein- 
statement, in  some  sHght  degree,  of  the  movements  made 
on  a  large  scale  at  the  time  of  the  original  experience.  He 
challenges  any  one  to  think  the  sound  of  o  with  closed  Ups, 
and  regards  failure  to  do  so  as  proof  of  his  contention  that 
all  thinking  is  in  terms  of  a  reinstatement  of  some  move- 
ment. Most  recent  investigators,  however,  incline  to  the 
view  that,  while  imagery  is  much  more  restricted  than 
sensation,  most  individuals  have  memories  from  more 
than  one  sense,  many  from  two  or  more  in  approximately 
the  same  degree.  These  latter  individuals  will  use  the  type 
of  imagery  most  suited  to  the  problem  in  hand.  If,  for  ex- 
ample, one  both  paints  and  composes  music,  one  would 
plan  a  picture  in  visual  images  and  compose  in  musical 
tones.  While  one  or  more  types  may  be  lacking  in  most 
individuals,  and  one  or  more  be  preferred,  the  sharp  classi- 
fication into  visual,  auditory,  etc.,  seems  too  rigid  to  har- 
monize with  the  facts. 

Verbal  Imagery.  —  Two  major  forms  of  imagery  may  be 
distinguished,  the  verbal  and  the  concrete.  They  are  not 
mutually  exclusive  in  any  sense,  as  most  individuals  will 
use  the  verbal  in  more  abstract  thinking  and  in  cases  where 
they  must  describe  the  event  and  will  use  concrete  images 
on  other  occasions.  Words  may  be  presented  to  one's  self 
in  three  distinctly  different  ways. 


MEMORY  TYPES  261 

First,  by  revived  kinicsthetic  impressions,  the  sen- 
sations that  come  from  the  vocal  organs  when  the 
word  is  spoken  are  revived  in  memory.  This  may, 
in  certain  individuals  and  at  times  in  all,  take  the 
form  of  the  sHght  movements  of  the  vocal  organs  that 
were  mentioned  by  Strieker. 

Secondly,  in  revived  auditory  sensations  of  the  words 
as  they  might  be  heard  when  spoken  by  one's  self  or 
another. 

It  is  also  possible  to  recall  the  words  as  they  would 
look  on  the  printed  page.    This  visual  recall  is  not  fre- 
quent as  an  antecedent  of  speech,  but  where  one  at- 
tempts to  recall  letters  or  figures  it  may  predominate. 
It  will  also  be  used  when  one  is  Ustening  to  a  language 
more  familiar  in  reading  than  in  speech. 
Concrete  Imagery.  —  In  concrete  imagery  any  one  of  the 
senses  may  predominate  and  several  may  be  used  simul- 
taneously.    Professor    Griffitts,    in   an  unpubhshed  study 
of  the  imagery  of  more  than  one  hundred  students,  found 
that  more  than  ninety  per  cent  relied  mainly  upon  visual 
imagery.    Next  in  order  of  importance  were  auditory  and 
motor,  with  less  than  five  per  cent  of  each.     Even  these, 
for  the  most  part,  used  vision  when  recalUng  concrete  im- 
pressions, but  made  large  use  of  verbal  imagery.    Only  one 
man  was  found  in  one  hundred  and  twelve  cases  who  had 
no  visual  imagery.     While  there  were  only  very  few  who 
were  confined  to  one  sense  in  recall,  there  were  great  dif- 
ferences in  the  degree  of  clearness  of  the  different  forms  of 
sensory  imagery.      Some   individuals   recall   and   imagine 
events  visually  with  almost  the  vividness  of  real  objects. 
Others  have  very  indefinite  images,  which  suggest  rather 
than  reproduce  events.    There  is  a  marked  difference  be- 
tween dominance  and  definiteness  of  imagery.    Certain  in- 


262        FUNDAMENTALS   OF  PSYCHOLOGY 

dividuals  who  use  almost  no  imagery  but  visual,  have  less 
vivid  visual  images  than  others  who  are  predominantly 
auditory  or  motor,  and  have  only  secondary  visual  mem- 
ories. Another  indication  that  imagery  is  not  exclusively 
of  one  sense  is  the  fact  that  individuals  with  well-developed 
auditory  imagery  also  are  Hkely  to  have  vivid  visual  im- 
agery. One  cannot  speak  of  types,  as  the  older  men  did, 
with  the  imphcation  that  if  one  has  a  well-developed  im- 
agery from  one  sense,  one  is  Hkely  to  be  defective  in  others. 
Rather,  it  is  true  that  men  differ  in  the  sense  that  they 
use  most  frequently  in  memory  and  imagination  and  also 
differ  in  the  vividness  or  effectiveness  of  the  sense  that  is 
dominant. 

The  Origin  of  Imagery  Types.  —  The  differences  are 
probably  due  in  part  to  heredity  and  in  part  to  training. 
Evidence  may  be  adduced  by  a  few  cases  in  favor  of  a 
hereditary  predisposition.  Dodge,  who  is  almost  alto- 
gether without  auditory  imagery,  reports  that  his  parents 
had  the  same  lack.  The  inheritance  of  musical  ability, 
which  in  all  probabiHty  depends  upon  the  possession  of 
auditory  imagery,  may  also  be  cited  as  evidence  of  a  heredi- 
tary tendency.  On  the  other  side,  training  has  been  shown 
in  several  individual  cases  to  have  exerted  an  influence  in 
changing  the  memory  type.  Particularly  with  school  chil- 
dren, it  is  found  that  they  can  be  trained  to  considerable 
facility  in  types  of  imagination  in  which  they  possess  no 
natural  skill.  Even  in  adults  long  practice  gives  results  in 
the  development  of  new  forms  of  imagery.  A  student  who 
cannot  spell  because  he  cannot  see  the  words  in  his  mind's 
eye  can  by  repeated  efTort  bring  himself  to  visuaHze  the 
words,  with  some  degree  of  improvement  on  the  practical 
side.  It  does  not  follow,  however,  that  spelling  is  abso- 
lutely dependent  upon  the  possession  of  the  visual  type. 


MEMORY  TYPES  263 

It  seems,  then,  that  both  heredity  and  training  may  play  a 
part  in  determining  the  mental  type,  —  certainly  training 
may  change  what  is  given  by  heredity. 

Synaesthesia.  —  A  curious  occasional  phenomenon  is  the 
close  connection  in  certain  individuals  between  objects  or 
sensations  of  different  senses.  Numerous  cases  have  been 
recorded  in  which  letters  have  colors  closely  connected 
with  them  in  the  mind  of  an  individual:  a  may  be  pink, 
0  green,  etc.  Words  also  either  have  a  color  of  their  own, 
or  take  on  the  color  of  the  letters  that  make  them  up. 
Several  cases  have  been  reported,  too,  in  which  musicians 
have  colors  aroused  by  certain  tones  or  tone  combinations, 
and  these  may  seem  to  be  essential  components  of  the  tone 
effects.  Thus  Myers  reports  that  Scriabin,  the  Russian 
composer,  had  a  different  color  for  the  different  keys.  The 
major  keys  of  C,  D,  B,  and  F#  have  the  colors  of  red, 
orange-yellow,  blue,  and  violet,  respectively,  and  the 
effects  are  so  strong  that  he  desired  to  have  his  compo- 
sitions rendered  to  the  accompaniment  of  colored  lights 
that  should  flood  the  hall  from  concealed  lamps.  In 
another  striking  case  odors  were  associated  with  colors;  in 
fact,  were  often  only  perceived  through  their  color  associa- 
tions. 

Two  theories  have  been  held  to  account  for  the  phe- 
nomenon: one  that  the  connections  have  been  made 
through  association,  the  other  that  it  is  fundamental  and 
perhaps  due  to  the  fact  that  there  is  some  common  feel- 
ing or  other  element  which  serves  to  connect  the  two  sen- 
sory components.  The  second  theory,  if  true,  must  admit 
that  individuals  who  possess  this  idiosyncrasy  seldom  agree 
as  to  the  colors  that  shall  be  associated  with  a  particular 
tone,  although  each  person  who  has  it  feels  that  it 
is  universal  and  necessary.     The  association  theory  is  as 


264        FUNDAMENTALS   OF  PSYCHOLOGY 

yet  equally  unproven,  although  a  few  characteristic  peculi- 
arities suggest  that  the  connection  of  colors  with  letters  or 
tones  may  be  due  to  old  habits.  Thus  in  three  sisters  whom 
I  investigated,  one  of  the  few  correspondences  was  thatj 
was  said  to  have  a  gritty  brown  color  to  all  three,  an  obvi- 
ous connection  with  jug.  How  far  heredity  plays  a  part, 
how  far  there  may  be  more  fundamental  common  charac- 
teristics between  the  sensations  connected,  and  how  far  the 
phenomenon  may  be  merely  the  result  of  early  associations 
is  still  largely  a  matter  of  conjecture. 

In  brief,  the  quahties  of  memory  and  imagination  are 
the  same  as  the  quahties  of  sensations,  a  httle  less  numer- 
ous, with  not  quite  the  same  distinctness,  but  with  no  new 
quahties  added.  These  impressions  are  recalled  through 
laws  of  association  not  so  very  different  from  the  laws  of 
habit,  and  are  woven  together  in  new  patterns  to  give  fea- 
tures of  remembered  events  that  suit  the  purpose  of  the 
moment,  or  to  make  new  constructions  of  imagination  or 
reason.  As  is  to  be  seen  in  the  next  chapter,  these  con- 
structions are  subordinate  to  more  general  control  in  the 
same  degree  and  by  the  same  laws  as  sensations. 

REFERENCES 

Galton:    Inquiry  into  Human  Faculty,  pp.    56-149.      Every- 
man's Library  ed. 
Stricker:  Studien  liber  Sprachvorstellungen. 
Woodworth:  Psychology,  Ch.  XVI. 
MacDougall:  Primer  of  Physiological  Psychology. 


CHAPTER  IX 

ATTENTION 

So  far  we  have  been  tracing  the  influences  of  the  envi- 
ronment, of  past  experience,  and  of  evolution  and  heredity, 
in  determining  the  actions  and  the  mental  states  of  man. 
These  provide  the  materials  of  mind  and  the  basic  ten- 
dencies of  action.  One  other  characteristic  of  conscious- 
ness and  action  must  be  discussed.  This  is  the  fact  of  se- 
lection which  is  known  both  popularly  and  by  psycholo- 
gists as  attention.  The  stimuH  that  affect  the  sense  organs 
do  not  exert  an  influence  directly  proportional  to  their 
energy  or  to  the  frequency  with  which  they  have  been  re- 
peated. Certain  stimuH  will  produce  an  effect  at  one  time 
that  they  will  not  produce  at  another.  A  faint  stimulus  of 
a  certain  kind  will  have  a  greater  effect  than  an  intense 
stimulus  of  another  kind.  This  difference  can  be  seen  both 
in  the  movements  that  are  excited  and  by  the  fact  that 
one  will  affect  consciousness,  the  other  not.  This  fact  of 
selection  must  itself  be  given  an  explanation.  We  must 
determine  the  laws  under  which  selection  takes  place  and 
if  possible  trace  the  changes  to  their  causes. 

The  Nature  of  Attention 

The  fact  of  attention  is  apparent  to  every  one  and  at  all 
times.  As  one  looks  out  over  a  landscape,  one  feature  after 
another  is  noticed;  as  one  sits  at  the  study  table  working, 
the  noise  of  the  street,  and  memories  of  all  kinds,  will  from 
time  to  time  intrude  themselves  and  crowd  out  the  page  of 
265 


266        FUNDAMENTALS   OF  PSYCHOLOGY 

the  book,  even  if  the  eyes  still  wander  along  the  Hnes  of 
print  and  all  the  other  physical  conditions  of  reading  are 
unchanged.  In  both  cases  the  mental  content  varies  be- 
cause of  changes  within  rather  than  without  the  body.  We 
are  conscious  at  any  time  of  only  a  fraction  of  the  things 
that  might  be  observed.  Many  sensory  experiences  pass 
unnoticed  unless  we  look  for  them  particularly.  The  vast 
majority  of  objects  presenting  themselves  to  the  eyes  are 
not  seen,  and  many  of  the  sounds  that  fall  upon  the  ear 
are  not  heard.  Only  the  few  that  appeal  to  us  at  the 
moment  are  selected. 

Consciousness  as  a  whole  has  been  likened  by  Wundt  to 
the  field  of  vision.  There  is  a  point  of  clearest  vision  in 
the  centre  where  the  cones  are  very  close  together,  and  a 
gradually  decreasing  clearness  as  one  passes  outward  to  the 
circumference.  The  point  of  maximum  attention  corre- 
sponds to  the  fovea  in  the  field  of  vision,  the  other  regions 
of  consciousness  to  the  periphery.  Attention  may  wander 
over  the  field  of  consciousness  in  much  the  same  way  that 
the  eye  wanders  over  the  field  of  vision.  The  common 
characteristic  of  foveal  vision  and  attention  is  the  increased 
clearness  that  comes  in  both  cases.  As  a  result,  contours 
and  differences  in  intensity  between  parts  are  better  dis- 
criminated. Temporal  effects  of  attending^to  a  sensation 
have  been  noted  in  hastening  its  entrance  and  in  keeping 
it  a  little  longer  in  consciousness.  All  these  differences 
would  increase  the  importance  of  the  impression  attended 
to  as  compared  with  one  that  is  not  attended  to. 

Does  Attention  Increase  the  Intensity  of  Sensation?  — 
What  change  does  attention  bring  about  in  the  content  of 
consciousness?  The  answer  is  to  be  found  in  the  observa- 
tion of  one's  own  state  as  one  attends,  rather  than  in  a 
verbal  description.     Certain  it  is  that  the  object  or  event 


ATTENTION  267 

attended  to  becomes  in  every  way  more  important  for 
consciousness;  it  stands  out  above  the  others  at  the  mo- 
ment, is  also  more  Ukely  to  be  remembered  and  to  start 
new  trains  of  thought.  The  character  of  the  change  can 
be  given  only  by  comparing  it  with  other  known  changes 
and  indicating  the  similarities  and  differences  between 
them.  In  many  respects  it  is  like  an  increase  in  intensity. 
Increase  in  the  intensity  of  a  physical  stimulus  also  make 
it  more  likely  to  affect  consciousness,  increases  the  prob- 
ability that  it  will  be  remembered,  and  quickens  the  reac- 
tion to  it.  That  attention  and  increase  in  intensity  are 
not  identical  is  evident  from  the  fact  that  we  never  mistake 
one  for  another.  We  never  assume  that  a  sound  has  actu- 
ally become  louder  when  we  have  only  turned  attention  to 
it.  On  the  other  hand,  it  is  certain  that  the  two  changes 
have  much  the  same  practical  effects;  both  attention  and 
intensity  make  the  experience  more  important  for  con- 
sciousness. Attention  also  produces  an  increased  clearness 
of  outline.  In  this  respect  it  has  an  effect  similar  to  that 
due  to  increased  closeness  of  the  nerve  terminations. 

The  Distribution  of  Clearness.  —  Much  discussion  has 
arisen  in  the  last  few  years  among  the  people  who  would 
make  clearness  the  primary  characteristic  of  the  attentive 
consciousness,  as  to  the  way  in  which  clearness  is  distrib- 
uted over  the  field  of  consciousness.  Titchener  regards 
clearness  as  one  of  the  fundamental  attributes  of  sensa- 
tion on  the  same  level  with  quality  or  intensity.  He  first 
asserted  that  there  are  at  any  moment  in  consciousness 
but  two  degrees  of  clearness,  —  the  centre  upon  which  at- 
tention is  fixed  and  the  hazy  background.  This  first  state- 
ment was  softened  in  large  measure,  however,  by  the  ad- 
mission that  there  might  be  differences  in  clearness  in  both 
upper  and  lower  levels,  separated  by  a  marked  break  in 


268        FUNDAMENTALS   OF  PSYCHOLOGY 

the  degree  of  clearness  between  the  two  levels.  Under  the 
criticism  of  Wirth,  who  asserted  that  consciousness  grades 
off  gradually  from  the  clearest  point  to  the  most  obscure, 
Titchener  renewed  his  investigation  of  the  question,  and' 
found  that  there  was  a  difference  between  individuals  in 
this  respect,  that  certain  people  belonged  to  the  two-level 
type,  others  had  a  number  of  different  levels  or  even  ap- 
proached the  gradual  passage  from  maximum  to  minimum 
clearness  that  Wundt  had  described  as  the  universal  type. 
Attention  as  Selection.  —  The  process  of  selection  re- 
quires less  description,  although  in  its  ramifications  it  prob- 
ably takes  more  different  forms  and  is  a  more  important 
psychological  fact  than  clearness.  In  part,  selection  re- 
sults in  an  increase  in  the  clearness  of  the  content,  —  an 
element  obscure  at  one  moment  becomes  clear  at  the  next; 
in  part,  the  process  selected  rises  from  complete  obscurity 
to  a  dominating  place  in  consciousness,  a  possible  content 
is  made  actual  at  one  stroke.  We  are  concerned  with  it 
primarily  in  its  latter  form  when  a  stimulus  that  has  been 
present  but  ineffective,  suddenly  rises  to  a  prominent  place. 
In  later  discussions  it  will  be  seen  that  the  fact  of  selection 
is  of  fundamental  importance.  Not  only  stimuH  but  also 
ideas  are  selected.  Control  of  association  is  selection  and 
through  ideas  we  reach  decisions  and  govern  actions.  It 
will  be  found,  too,  that  many  of  the  same  principles  and 
the  same  conditions  are  involved  in  the  selection  of  these 
higher  or  more  complicated  processes,  that  are  involved  in 
the  simpler  operations  with  which  we  are  dealing  here. 

Motor  Aspects  of  Attention 

Motor  Concomitants  of  Attention.  —  If  we  turn  from  the 
function  to  the  subordinate  features  of  attention,  we  find 
that  a  characteristic  quality  is  given  the  experience  of  at- 


MOTOR  ASPECTS   OF  ATTENTION         269 

tending,  both  for  the  one  attending  and  the  observer,  by 
accompanying  movements.  These  are  of  varied  sorts  and 
degrees.  Most  important  in  practice  are  the  actions  in- 
volved in  the  accommodation  of  the  sense  organs.  As  one 
attends,  the  organ  adjusts  itself  to  give  the  best  possible 
conditions  for  observation.  The  eye  at  once  turns  so  that 
the  object  falls  upon  the  fovea,  the  lens  without  further 
thought  is  given  the  right  curvature,  the  eye  is  in  conse- 
quence focussed  for  the  distance  of  the  object,  and  the  two 
eyes  are  converged  to  permit  both  to  see  it  with  the  fovea. 
Each  of  these  adjustments  is  made  without  specific  inten- 
tion and  usually  without  knowledge  that  they  have  been 
or  are  being  made.  One  cannot  contract  the  ciliary  mus- 
cle to  adjust  the  lens,  by  direct  impulse.  The  only  way  to 
move  the  muscle  is  by  attention  to  objects.  If  one  attends 
to  a  distant  object,  the  muscle  relaxes;  if  one  attends  to  a 
near  object  closely,  it  contracts,  but  this  is  the  only  way 
that  it  can  be  made  to  act.  The  same  statement  holds  in 
less  degree  of  turning  and  converging  the  eyes.  The  move- 
ment follows  at  once  upon  attention  and  is  always  a  result 
of  attending.  In  the  other  senses,  the  adjustments  of  the 
sense  organs  are  less  striking,  although  still  present.  The 
head  is  turned  toward  the  source  of  sound  to  increase  the 
certainty  of  receiving  the  tones.  This  is  particularly  no- 
ticeable if  one  ear  be  defective.  The  head  will  then  be 
turned  to  one  side  when  Hstening,  to  receive  as  much  as 
possible  of  what  is  being  said.  The  muscles  in  the  middle 
ear  probably  have  a  protective  function  only,  and  play 
little  part  in  attentive  listening.  When  one  is  asked  if  one 
notices  smoke,  sniffing  follows  automatically  to  bring  as 
much  air  as  possible  to  and  through  the  nostrils.  Simi- 
larly, when  a  cook  passes  critical  judgment  upon  a  product 
of  his  art,  the  substance  is  pressed  more  closely  against 


270        FUNDAMENTALS   OF  PSYCHOLOGY 

the  tongue  by  bringing  the  tongue  against  the  roof  of  the 
mouth.  In  feehng  a  surface  the  hands  are  kept  in  motion, 
in  order  that  the  slighter  irregularities  may  be  noticed.  In 
the  blind  this  frequently  develops  into  a  series  of  slight 
movements  of  the  finger  tips  made  automatically  and  al- 
most unconsciously.  Comparing  weights  calls  out  similar 
lifting  movements  of  the  whole  arm.  Each  sense,  then, 
has  a  series  of  accommodatory  movements  that  make  the 
sensation  more  adequate  and  complete,  movements  that 
come  without  thought,  are  an  immediate  outcome  of  at- 
tending, of  the  desire  to  know  more  about  the  object  in 
which  one  is  interested. 

Mimetic  Movements.  —  Another  characteristic  group  of 
movements  is  carried  out  by  the  voluntary  muscles  of  all 
parts  of  the  body,  which  depend  for  their  character  upon 
the  nature  of  the  thing  attended  to.  Every  movement 
that  is  absorbing  attention  or  that  is  watched  attentively 
tends  to  induce  or  be  accompanied  by  similar  movements 
on  the  part  of  the  onlooker.  Thus  if  one  is  watching  an 
athletic  contest  closely,  it  is  probable  that  one  will  make 
sHght  movements  in  imitation  of  the  contestants.  This 
tendency  to  act  out  ideas  explains  many  of  the  cases  of  mind- 
reading  and  similar  processes  which  approach  the  occult. 
SUght  movements  made  without  the  knowledge  or  intention 
of  the  one  and  interpreted  without  the  knowledge  of  the 
other  serve  as  a  basis  for  the  communication.  The  capacity 
for  interpreting  these  sHght  unconscious  movements  is 
found  in  animals  as  well  as  in  man.  The  feats  of  "  Khige 
Hans''  and  the  Elberfeld  horses,  which  seemed  to  do  sums 
and  perform  other  wonders,  were  found  on  closer  examina- 
tion to  depend  in  part  upon  noticing  signals  from  the 
trainers  which  were  given  without  the  knowledge  of  the 
trainers.    Thus  a  horse,  when  given  a  sum  on  the  board, 


MOTOR  ASPECTS   OF  ATTENTION         271 

would  begin  to  stamp  and  continue  the  movements  until 
the  trainer  indicated  his  satisfaction  by  some  slight  move- 
ment. These  movements  of  the  muscles  of  the  face  and  of 
the  bodily  attitude  constitute  a  large  element  in  the  appre- 
ciation of  the  mental  attitude  of  a  companion. 

Diffuse  Motor  Discharges.  —  Still  another  large  group 
of  movements  of  the  voluntary  muscles  accompanying 
attention  is  constituted  by  a  contraction  of  most  of  the 
muscles  of  the  body,  due  to  a  general  discharge  of  impulses, 
a  sort  of  overflow  of  motor  excitations.  As  one  attends 
strongly  to  any  object  one  becomes  tense,  the  brow  wrinkles, 
the  teeth  are  set,  the  fists  may  be  clenched.  The  degree  of 
tension  increases  with  the  degree  of  attention.  One  uses 
the  feehngs  of  strain  subjectively  as  a  measure  of  the  amount 
of  attention,  and  one  also  regards  the  amount  of  contraction 
as  a  measure  of  the  attention  of  another.  It  is  not  neces- 
sarily true  that  the  efficiency  of  attention  is  measured  accu- 
rately by  the  amount  of  contraction  or  of  the  resultant 
feeling  of  strain.  These  strains  seem  to  be  more  pro- 
nounced when  the  resistance  to  be  overcome  is  great,  rather 
than  when  one  is  attending  to  the  best  advantage.  But 
it  is  taken  by  the  individual  himself  as  an  indication  of  the 
effort  that  he  is  exerting  in  attention,  or  of  the  effort  that 
he  is  exerting  in  any  field.  Closely  connected  with  these 
general  contractions  and  accompanying  marked  attention 
is  the  inhibition  of  all  movements.  Some  individuals  must 
stop  any  movement  they  may  be  engaged  in  when  they 
begin  to  attend,  and  in  all  there  is  checking  of  movements 
when  attention  becomes  close.  It  can  be  noticed  most 
clearly  in  an  audience.  When  inattentive,  there  is  always 
a  sound  made  by  the  rustle  of  garments,  by  other  move- 
ments, each  in  itself  too  slight  to  make  a  noticeable  noise, 
but  which  in  the  sum  produce  a  marked  disturbance.    As 


272        FUNDAMENTALS   OF  PSYCHOLOGY 

soon  as  the  audience  becomes  attentive,  all  this  stops  and 
silence  ensues.  These  inhibitions  are  of  value  in  hstening 
for  faint  sounds;  and  in  many  other  sorts  of  attention  they 
may  increase  the  effectiveness  of  the  sense  in  some  degree. 
While  necessary  for  audition,  they  have  become  an  accom- 
paniment of  all  attending. 

Changes  in  non-voluntary  physiological  processes  also 
are  present.  These  are  perhaps  most  strikingly  seen  in  the 
checking  of  respiration.  As  one  attends,  the  breathing  is 
checked.  In  a  short  period  of  profound  attention  the  breath 
will  be  held  and  a  sigh  or  deep  inspiration  will  follow  relaxa- 
tion. In  longer  periods  the  breathing  first  becomes  quick 
and  shallow;  in  still  longer  periods  it  is  slower,  but  also 
more  shallow  than  usual.  Similarly,  there  are  changes  in 
the  circulation.  The  heart  beats  more  quickly,  the  blood 
vessels  contract  in  the  periphery  and  expand  in  the  brain, 
the  blood  pressure  rises,  the  pupils  are  dilated,  tears  are 
secreted  which  give  the  bright  eye  of  interest.  Each  of 
these  movements  renders  the  organism  more  efficient. 
Holding  the  breath  removes  the  noises  of  respiration  that 
might  interfere  with  faint  sounds.  The  quicker  heart  beat 
and  increased  circulation  in  the  brain  prepare  for  apprecia- 
tion of  the  conditions,  and  for  the  activity  that  may  follow. 
Attention,  then,  is  a  physical  as  well  as  a  mental  process. 
Accompanying  increased  appreciation  of  sonie  one  sensation 
or  stimulus  is  a  widespread  irradiation  of  impulses  to  the 
muscles.  These  serve  to  increase  bodily  capacity,  are  an 
indication  to  an  onlooker  of  attending  and  of  the  direction 
of  attention.  The  sensations  of  strain  which  come  from  the 
contractions  are  assumed  to  measure  the  degree  of  attention. 
Most  so-called  mental  tension  is  physical,  due  to  these  mus- 
cular contractions. 


ATTENTION  IS   UNITARY  273 

Limits  of  Attention 

The  Range  of  Attention.  —  One  of  the  concrete  problems 
that  has  been  frequently  discussed  and  most  often  measured 
in  connection  with  attention  is  its  range,  the  number  of 
things  that  may  be  perceived  at  once.  The  experiments 
have  been  carried  out  by  making  very  brief  exposures  of  a 
number  of' objects,  and  asking  an  observer  how  many  have 
been  seen.  The  exposure  is  limited  to  a  fifth  of  a  second  or 
less,  a  time  which  does  not  permit  any  change  of  the  atten- 
tion or  movement  of  the  eye.  Results  agree  that  four  or 
five  objects  may  be  seen  at  a  single  exposure.  It  is  interest- 
ing to  note,  too,  that  the  number  of  objects  that  may  be 
seen  is  relatively  independent  of  the  size  or  complexity  of 
the  object.  One  dot,  a  group  of  three  or  more  that  makes 
some  regular  figure,  a  letter,  or  a  small  word  are  all  seen 
with  approximately  the  same  ease.  In  fact,  a  short  word 
is  more  certain  to  be  recognized  than  a  single  letter.  What 
constitutes  a  single  object  is  fundamentally  that  it  has  been 
used  or  treated  as  a  single  thing,  rather  than  its  physical 
complexity.  The  number  of  auditory  impressions  is  slightly 
greater  than  the  visual,  but  they  must  of  course  be  given 
in  succession.  Eight  single  ticks  of  a  metronome  may  be 
appreciated  when  heard  without  rhythm,  and  when  com- 
bined in  a  rhythm  as  many  as  forty  —  five  groups  of  eight 
each  —  can  be  heard  in  a  single  unit.  The  experiments  also 
make  it  probable  that  the  objects  are  not  really  seen  all 
at  once  but  that  they  are  counted  after  the  exposure  in  the 
immediate  memory  or  memory  after-image.  Careful  exami- 
nation of  the  process  of  attending  to  objects  exposed  for 
an  instant  shows  that  the  real  study  of  the  object  is  made 
after  the  exposure.  Impressions  persist  in  the  memory 
after-image    with    considerable    vividness    for    some    two 


274        FUNDAMENTALS   OF  PSYCHOLOGY 

seconds,  long  enough  to  count  the  five  objects  successively. 
One  really  attends,  then,  to  but  a  single  object  at  a  time, 
but  five  successive  acts  of  attention  can  be  completed  before 
the  vivid  memory  image  disappears. 

Much  the  same  problem  has  been  raised  with  reference 
to  how  many  processes  may  be  carried  on  at  once.  Occa- 
sionally one  reads  that  some  man  is  able  to  do  two  or  more 
things  at  a  time.  Csesar  was  said  to  dictate  to  several 
secretaries  at  once,  and  similar  tales  are  told  of  others. 
Experiments  made  to  test  the  point  all  indicate  that  more 
than  one  process  may  be  carried  on  at  one  time,  but  only 
provided  some  of  them  are  sufficiently  automatic  to  require 
no  attention.  Thus  it  is  possible  to  write  from  dictation  and 
add  mentally  at  the  same  time,  and  the  time  required  for 
doing  both  will  be  less  than  the  sum  of  the  times  for  doing 
each  separately.  If  it  is  attempted  to  do  three  things 
simultaneously  or  to  do  two  things  even  one  of  which  has 
not  become  pretty  thoroughly  automatic,  more  time  is 
required  to  accomplish  them  together  than  separately.  Here 
again  it  seems  that  one  can  attend  to  but  one  thing  at  a 
time,  although  it  is  possible  to  start  one  series  of  activities 
and  let  it  go  on  of  itself  while  one  attends  to  something 
else  for  a  time.  Attention  changes  from  one  to  the 
other  just  often  enough  to  keep  the  different  processes 
going. 

The  Duration  of  Attention.  —  Another  question  of  similar 
character  is  how  long  one  may  attend  without  a  break. 
This  question  has  been  given  different  answers  at  different 
times,  and  the  answer  depends  in  part  upon  what  is  meant 
by  the  question.  Speaking  roughly,  one  may  attend  to  the 
same  general  subject,  may  read  a  book,  for  example,  for  an 
indefinite  period.  Careful  observation  of  the  course  of 
attention  to  faint  stimuli,  however,  shows  that  they  will 


FLUCTUATIONS  OF   ATTENTION  275 

be  appreciated  only  for  short  periods;  they  cease  to  be 
noticed  in  the  intervals.  Thus  if  one  Hsten  to  the  ticking  of 
a  watch  or  the  faint  tone  of  a  telephone  at  a  little  distance, 
it  will  be  observed  that  the  sound  will  be  heard  for  an  instant 
and  then  will  disappear,  and  these  alternations  will  continue 
as  long  as  one  Ustens.  Similar  fluctuations  are  present  dur- 
ing the  observation  of  faint  visual  stimuh.  The  explanation 
of  these  fluctuations  has  been  variously  given  as  due  to 
fatigue  in  the  sense  organs,  either  of  the  muscles  or  of  the 
sensory  endings,  to  fatigue  of  the  sensory  regions  in  the 
cortex,  or  to  changes  in  the  blood  supply  to  the  cortex,  and 
even  to  fluctuations  of  mental  energy.  The  explanation 
cannot  be  regarded  as  completely  agreed  upon,  although 
considerable  evidence  has  been  given  in  favor  of  all  but  the 
last  theory.  What  is  probably  more  truly  a  fluctuation  of 
attention  is  seen  if  one  will  keep  a  record  of  the  time  that 
one  can  fix  upon  some  single,  simple  object,  a  dot  or  a  single 
tone.  It  will  be  seen  that  the  single  object  will  dominate 
consciousness  for  only  a  second  at  the  most,  then  something 
in  the  neighborhood  will  crowd  out  the  first,  or  a  memory  of 
some  event  of  the  past  will  intrude  to  exclude  it.  Between 
each  of  the  other  events,  attention  will  go  back  to  the  dot. 
The  observer  wiU  be  sure  that  the  dot  has  been  present  aU 
the  time,  but  it  wiU  not  have  been  attended  to.  It  seems 
that  one  can  attend  strictly  and  definitely  for  a  very  short 
time,  a  second  or  so.  In  addition  there  are  waves  of  in- 
creased effectiveness  which  come  and  go  every  six  to  ten 
seconds.  These  probably  depend  upon  fluctuating  physio- 
logical processes,  central  or  peripheral.  If  by  attending  to 
the  same  thing  is  meant  attending  to  a  general  subject  that 
contains  changing  elements,  it  is  possible  to  attend  for 
several  hours  —  the  length  of  time  depending  upon  the 
nature  of  the  material,  the  strength  of  the  observer,  and 


276        FUNDAMENTALS   OF  PSYCHOLOGY 

other  conditions.     If,  however,  we  mean  attention  to  one 
thing  exclusively  one  can  attend  only  a  second  or  less. 

Attention  and  Distraction.  —  It  is  very  interesting  to 
note  that,  on  the  whole,  attempts  to  distract  or  to  interfere 
with  the  attention  of  an  individual  usually  result  not  in 
decreased,  but  in  increased  efficiency.  Psychologically  this 
was  first  noticed  when  attempts  were  made  to  measure 
attention  by  determining  how  much  distraction  was  re- 
quired to  prevent  the  observer  from  performing  some  pre- 
scribed task.  Almost  without  exception,  experiments  of 
this  type  show  an  increase  rather  than  the  expected  diminu- 
tion in  efficiency  during  the  distraction.  A  long  investiga- 
tion by  Morgan  has  given  an  indication  of  the  reason  for 
this  result.  Morgan  had  his  observers  make  complicated 
calculations  while  records  were  kept  of  the  breathing  and 
of  the  pressure  which  was  made  in  writing  answers.  The 
individuals  undergoing  the  test  would  work  undisturbed 
for  a  time,  and  then  a  phonograph  would  be  started  or  other 
disturbing  impressions  introduced.  The  course  of  the  work 
showed  that  there  was  in  most  cases  an  increase  in  the 
amount  of  work  done.  This  increase  would  continue  as 
long  as  the  distraction  lasted  and  the  rate  and  accuracy  of 
work  would  then  decline  below  that  which  preceded  the 
distraction.  The  explanation  was  found  in  a  study  of  the 
records  of  physiological  processes.  In  writing,  pressure 
upon  the  paper  increased  at  the  moment  of  distraction, 
the  respiration  became  labored  and  showed  that  the  observer 
was  aiding  his  work  by  slight  movements  of  the  vocal  organs. 
All  showed  clearly  that  there  was  increased  motor  tension. 
This  was  an  indication  of  increased  nervous  action,  which 
was  sufficient  to  augment  capacity  to  a  point  which  more 
than  overcame  the  effect  of  the  distraction,  although  at  the 
expense  of  greater  fatigue.    One  can  parallel  these  results 


CONDITIONS   OF  ATTENTION  277 

in  daily  work.  Occasionally,  and  in  some  individuals  gen- 
erally, a  disturbance  will  increase  the  capacity  for  work. 
The  fact  that  the  greater  amount  of  work  is  at  the  expense 
of  greater  fatigue  probably  makes  it  undesirable  to  work  in 
a  disturbing  noise  unless  necessary,  but  when  necessary  the 
increased  accomplishment  compensates  for  the  discomfort. 

The  Conditions  of  Attention 

Objective  Conditions.  —  The  underlying  causes  or  con- 
ditions of  attention  are  to  be  found  in  the  antecedents  of 
the  attending  process  in  the  individual  himself  and  in  the 
material  that  offers  itself  from  the  outside  world.  On  the 
one  hand,  the  individual  attends  because  he  is  at  the 
moment  or  in  general  of  such  a  character  that  he  must 
attend  to  the  particular  thing  at  the  particular  time;  on 
the  other  hand,  the  characteristics  of  some  stimulus  and 
the  general  nature  of  the  environment  are  such  that  he 
cannot  avoid  noticing  it.  If  one  asks  why  any  individual 
notices  any  particular  thing  at  any  particular  time,  one 
will  find  the  answer  either  in  the  nature  of  the  environment 
or  of  the  individual.  The  objective  conditions  may  be 
found  in  the  attributes  of  the  stimuli  that  are  arousing  the 
sense  organs.  The  intensity,  size,  and  duration  of  a  stimulus 
and  its  contrast  with  the  surroundings  determine  whether 
or  not  it  is  likely  to  be  attended  to.  Loud  sounds,  bright 
lights,  strong  odors,  force  themselves  upon  consciousness; 
while  less  intense  stimuli  fail  to  attract  notice.  Contrast 
plays  a  part,  as  may  be  seen  from  the  fact  that  a  fairly 
bright  light  in  the  dark  attracts  as  much  attention  as  a 
briUiant  light  in  full  day  hght,  or  a  light  footstep  in  the 
silence  of  the  night  as  much  as  the  automobile  horn  in  the 
midst  of  a  dense  street  traffic. 

It  is  interesting  to  note  in  connection  with  objective 


278        FUNDAMENTALS   OF  PSYCHOLOGY 

factors  that  change  is  an  essential  element  in  arousing 
attention.  One  quickly  becomes  adapted  to  a  continuous 
stimulus  and  ceases  to  notice  it.  A  constant  light  is  un- 
noticed, but  the  shadow  cast  by  the  passing  of  a  cloud  at 
once  intrudes  upon  consciousness.  The  slight  noise  of  the 
burning  gas  drops  into  the  background,  and  as  Fechner 
pointed  out,  the  miller  is  oblivious  to  the  sound  of  his  mill, 
but  the  slightest  change  induced  by  a  defect  will  be  observed 
at  once.  The  cessation  of  the  stimulus  in  this  case  is  as 
effective  as  an  increase  in  the  sound.  A  clock  that  has  been 
ticking  unnoticed  in  the  study  will  be  noticed  when  it  stops 
and  the  last  few  ticks  will  be  heard,  —  sounds  that  would 
have  had  no  effect  upon  consciousness  had  they  not  ceased. 
The  decrease  in  the  size  of  an  object  moving  directly  away 
from  us  attracts  attention  almost  as  certainly  as  does  the 
increase  in  size  due  to  its  approach.  Each  of  these  effects 
of  objective  stimuli  might  be  explained  as  due  to  the  univer- 
sal characteristics  of  man  or  to  the  inherited  capacities  of 
his  nervous  system.  But  since  they  are  universal  to  all 
nervous  systems  it  seems  simpler  to  regard  them  as  of  objec- 
tive origin,  than  to  assert  that  man's  physical  organism  is 
adjusted  through  heredity  to  respond  to  stimuli  possessing 
much  energy  and  particularly  to  changes  in  the  amount  of 
energy  affecting  a  sense  organ. 

Subjective  Conditions.  —  More  truly  characteristic  of 
the  attention  processes  are  the  subjective  conditions.  We 
ordinarily  think  of  attention  as  a  free  act  by  which  we  turn 
to  one  thing  which  at  the  moment  it  pleases  us  to  notice, 
and  exclude  all  others.  But  frequently  there  is  no  conscious 
antecedent  desire,  and,  where  there  is,  the  desires  have  their 
antecedents  in  the  experience  of  the  individual  and  these 
are  to  be  regarded  as  the  real  conditions  of  his  attending. 
Sometimes  he  knows  that  he  desires  to  attend  because  of 


CONDITIONS   OF  ATTENTION  279 

the  antecedent  experiences;  more  often  he  first  finds  him- 
self attending  and  never  knows  why.  If  we  examine  the 
nature  of  attention  in  the  Hght  of  the  history  of  the  indi- 
vidual, we  may  distinguish  five  difTerent  groups  of  subjec- 
tive conditions. 

/.   Immediately  Preceding  Sensations.  —  The  first  group 
of  conditions  refers  to  the  immediately  preceding  sensa- 
tion.   This  can  be  best  illustrated  by  hearing  out  overtones. 
If  one  is  listening  for  an  overtone  in  a  note  played  on  the 
piano,  and  has  heard  another  note  of  the  same  pitch  just 
before,  he  will  distinguish  it  easily,  while  unless  he  has 
considerable  training,  he  cannot  hear  it  without  this  aid. 
So  if  one  desires  to  hear  the  first  overtone  of  c  on  the  piano, 
and  will  strike  c'  just  before  he  strikes  the  c,  he  will  notice 
the  overtone,  the  c',  without  difficulty.     Again  an  object 
just  seen  in  a  particular  place  will  strike  the  eye  when  one 
seeks  for  it,   where  previously  it  would  not  have  been 
noticed.    Very  much  the  same  statements  may  be  made  of 
the  idea  in  mind.     If  one  can  call  up  a  definite  image  of 
what  is  to  be  seen,  the  corresponding  object  will  be  noticed. 
It  is  probable  that  the  skill  of  the  practiced  observer  in 
hearing  overtones  is  due  to  the  fact  that  he  can  recall 
accurately  the  tone  that  he  is  to  hear.    This  definite  image 
replaces  the  sensation  in  its  effect  of  making  the  overtone 
likely  to  come  into  mind.    Similarly,  in  a  puzzle  picture,  to 
recall  the  concealed  face  in  its  actual  place  is  a  guarantee 
that  the  image  will  be  recognized  when  one  looks  a  second 
time.     The  image  definitely  recalled   serves   to  aid   the 
entrance  of  the  corresponding  percept,  in  the  same  way  as 
does  the  immediately  preceding  sensation. 

//.  Purpose  or  Mental  Attitude.  —  Most  important  and 
striking  of  these  subjective  conditions  is  the  influence  of  a 
factor  that  is  variously  designated  the  intention,  the  purpose, 


28o        FUNDAMENTALS   OF  PSYCHOLOGY 

or  the  question  in  mind  at  the  moment.  When  one  has  the 
intention  of  seeing  a  particular  thing,  that  thing  will  come 
to  consciousness.  If  some  one  suggests  that  you  look  for 
a  cell  in  the  field  of  a  microscope,  the  probability  that  you 
will  see  it  is  thereby  increased.  In  daily  life  this  purpose  is 
the  determining  factor  in  all  observation.  One  usually  sees 
or  hears  what  one  desires  to  see  or  hear,  or  what  harmonizes 
with  the  intention.  All  that  does  not  harmonize  with  that 
purpose,  unless  especially  favored  by  objective  conditions 
or  other  more  general  subjective  conditions,  might  as  well 
not  have  been  offered  to  the  senses.  If  one  is  interested  in 
what  an  individual  is  sa3nng,  one  will  not  notice  his  accent 
no  matter  how  unusual,  and  if  one  is  a  phonetician  and  in- 
tent on  the  study  of  the  pecuHarities  of  speech,  the  meaning 
may  be  altogether  lost.  One  does  not  notice  the  wall  paper 
in  a  room  unless  the  pattern  is  striking,  or  one  is  deciding  on 
wall  paper  for  one's  self  and  so  has  that  as  a  dominant  pur- 
pose at  the  time.  Some  objects  that  have  been  under  one's 
eyes  for  years  may  never  have  been  noticed  unless  some 
purpose  made  it  desirable.  To  use  a  famihar  instance,  the 
reader  cannot  say  without  looking  whether  the  four  on 
his  watch  is  iv,  4,  or  iiii,  in  spite  of  the  number  of  times  it 
has  been  looked  at.  One  looks  to  learn  the  time,  not  to 
see  how  the  numerals  are  printed,  and  sees  just  what  one 
looks  for,  and  nothing  else.  This  is  typical  of  most  observa- 
tion. Man  is  blind  to  what  does  not  correspond  to  his 
momentary  purpose. 

This  purpose  or  mental  attitude  may  be  aroused,  either 
from  without  or  from  within.  From  without  it  may  be  due 
to  a  question  asked  by  another,  or  to  some  task  that  has 
been  set,  or  problem  that  has  been  raised  by  one  in  au- 
thority. From  within,  the  purpose  usually  arises  by  a  sug- 
gestion from  something  that  has  been  seen.     Something 


CONDITIONS   OF  ATTENTION  281 

external  or  internal  starts  a  train  of  associations.  That 
raises  a  question  about  an  object  present,  and  one  looks  to 
the  object  for  an  answer.  The  answer  to  the  first  question 
suggests  another  problem,  and  thus  a  train  of  associations 
in  the  series  of  questions  leads  to  one  observation  after 
another.  Observation  is  most  frequently  the  result  of  a 
series  of  problems  self-set  for  solution.  When  one  has  the 
problem  or  the  question,  finding  the  answer  is  relatively 
easy.  Without  the  problem,  observation  is  indiscriminate 
and  relatively  unprofitable.  In  this  sense  thought  usually 
precedes  observation,  but  the  thought  itself  grows  out  of 
preceding  observation,  and  so  both  are  to  be  regarded  as 
parts  of  a  continuous  progression  in  which  each  thought 
suggests  attention,  and  the  results  of  each  attention,  a  new 
thought,  in  a  succession  broken  finally  by  the  irruption  of 
an  intense  stimulus  or  the  necessities  of  the  daily  fife,  and 
this  in  turn  starts  a  new  series  of  questions. 

///.  Education  and  Attention. — A  number  of  more 
remote  conditions  also  aid  in  preparing  an  individual  to 
attend  in  a  given  way  at  any  moment.  First  of  these  is  the 
earlier  training  and  previous  experience.  This  works  in 
two  ways:  in  the  first  place,  it  increases  capacity  for  obser- 
vation of  the  object  one  desires  to  know  about,  and  it  largely 
determines  what  one  desires  to  see.  The  skill  of  experts  in 
any  sort  of  observation  depends  upon  training.  The  skill 
of  expert  microscopists  in  any  realm,  of  musical  critics, 
of  tea  and  wine  tasters,  and  of  the  woodsman  in  tracking 
game  and  in  seeing  the  signs  of  the  forest,  all  comes  from 
training.  The  expertness  depends  in  part  upon  knowing 
what  to  look  for,  of  having  in  mind  the  problems  that  are 
to  be  solved  in  a  particular  connection;  in  part,  the  skill 
in  discrimination  grows  with  practice,  and  is  probably 
dependent  upon  a  number  of  physiological  factors.    Train- 


282        FUNDAMENTALS   OF  PSYCHOLOGY 

ing  has  also  obvious  effects  in  determining  what  sort  of 
stimuli  shall  be  selected  for  attention.  This  works  in  two 
ways.  In  the  first  place,  it  helps  to  raise  questions,  to  organ- 
ize purposes.  One  cannot  have  a  purpose  without  some  pre- 
liminary knowledge  of  the  thing  to  be  seen.  What  to  look 
for  in  animal  structures  is  known  in  any  considerable  degree 
only  by  individuals  with  some  training  in  zoology.  The 
trained  machinist  has  a  series  of  questions  in  mind  as  he 
begins  to  examine  the  engine  that  you  have  called  him  to 
repair,  and  with  these  problems  which  have  grown  out  of 
his  experience  he  looks  with  a  definite  series  of  purposes  and 
easily  discovers  the  source  of  trouble.  But,  secondly,  even 
with  no  definitely  conscious  purpose,  one  sees  the  things 
that  one  has  been  accustomed  to  deal  with,  or  that  one  has 
been  trained  to  see.  The  printer  without  effort  sees  details 
of  a  book  that  escape  the  ordinary  reader. 

IV.  Social  Forces  in  Attention.  —  Still  another  important 
group  of  influences  are  the  outgrowth  of  social  instincts. 
These  compel  respect  for  the  ideals  that  one  takes  from 
society,  and  make  one  strive  to  do  and  observe  certain 
things  because  of  the  fact  that  others  expect  such  behavior. 
The  student  attends  to  a  lesson  when  fatigued  or  when  the 
lesson  is  not  interesting  in  itself  because  he  desires  to  make 
a  good  record,  to  pass  an  examination.  Or  again,  a  man 
desires  to  make  a  good  record  for  the  sake  of  the  approval 
it  will  win  from  persons  he  respects.  Or  selecting  a  more 
permanent  aspect,  one  desires  to  obtain  a  satisfactory 
knowledge  of  a  subject  for  the  value  it  may  have  in  later 
years,  or  in  the  profession  that  has  been  adopted.  Again, 
however,  choice  of  a  profession  depends  largely  upon  the 
social  favor  that  the  profession  has  in  the  group  with  which 
one  is  acquainted.  Even  the  belief  that  the  particular 
subject  will  help  in  the  profession  is  often  taken  from 


CONDITIONS   OF  ATTENTION  283 

society.  It  is  a  preference  for  the  remote  as  opposed  to  the 
immediate  good,  but  the  more  remote  is  accepted  as  good 
and  obtains  impelling  force  because  of  the  influence  of 
society.  Society  approves  each  separate  step,  as  well  as 
the  attainment  of  the  end;  its  pressure  is  felt  throughout 
the  whole  course  of  the  attainment,  and  thus  at  once  guides 
and  compels  towards  that  end.  For  our  present  purpose 
it  may  be  regarded  as  the  source  of  all  attention  from 
constraint,  of  all  attention  against  one's  momentary 
desire. 

V.  Heredity  and  Attention.  —  A  final  condition  of  atten- 
tion, most  remote  in  time,  is  found  in  the  hereditary  dis- 
position. This  heredity  may  be  either  immediate,  as  in  the 
inheritance  of  individual  traits,  or  distant,  as  in  attention 
due  to  general  instinct.  The  former  is  less  easy  to  illustrate 
or  to  demonstrate,  but  it  seems  probable  from  special 
studies  in  attention  and  the  more  general  studies  in  heredity, 
mentioned  in  Chapter  V,  that  certain  of  the  tastes  of  an 
individual,  which  are  either  derived  from  the  natural  direc- 
tion of  his  attention  or  control  it  in  certain  respects,  are 
inherited  from  his  parents.  The  more  general  heredity  is 
seen  in  the  fact  that  one  attends  to  moving  objects,  to  per- 
sonal combats,  to  all  objects  that  are  likely  to  be  especially 
beneficial  or  injurious.  In  general,  if  one  asks  why  one 
attends  to  anything  at  a  particular  time,  the  answer  may 
be  found  in  the  nature  of  the  external  objects,  or  in  the  dif- 
ferent mental  states  at  the  moment,  in  the  experience  of 
the  immediate  or  of  the  remote  past,  and  finally  in  the 
inheritance  of  the  individual.  As  has  been  pointed  out, 
these  cooperate  in  many  ways  and  vary  independently  from 
moment  to  moment,  but  could  we  know  the  individual 
completely  in  all  of  his  characteristics,  his  past  history,  and 
the  influences  working  upon  him  from  the  environment,  it 


284        FUNDAMENTALS   OF  PSYCHOLOGY 

would  be  possible  to  say  fairly  closely,  even  with  our  present 
knowledge,  to  what  he  would  be  likely  to  attend. 

Attention  and  Association 

Control  of  Association.  —  Selection  is  quite  as  important 
in  controlling  the  course  of  the  associations  or  in  deter- 
mining the  ideas  that  shall  be  recalled  or  suggested,  as  in 
choosing  the  sensations  that  enter  consciousness.  It  is 
evident  that  the  mere  strength  of  connection  between  ideas 
would  give  only  a  rigid,  mechanically  determined  series  of 
thoughts  with  no  fiexibihty  or  adaptation  to  varying  con- 
ditions such  as  is  required  in  logical  thinking  or  purposeful 
imagination.  This  inadequacy  of  the  associative  connec- 
tions to  explain  the  real  course  of  thinking  has  led  many 
to  abandon  the  theory  altogether,  in  spite  of  the  fact  that 
in  some  degree  the  importance  of  old  relations  in  deter- 
mining what  shall  be  recalled  has  been  recognized  all 
through  the  history  of  psychology.  It  seems  more  in  har- 
mony with  the  facts  to  accept  the  view  that  fundamentally 
all  recall  goes  back  to  association,  that  each  impression  re- 
called must  be  suggested  by  the  preceding,  but  that  since 
each  idea  has  been  connected  with  many  others,  there 
must  be  other  conditions  which  have  united  to  bring  back 
just  that  idea  and  no  other;  or,  viewing  , the  process  in 
advance  of  the  recall,  the  arousal  of  one  idea,  connected 
with  the  thought  in  mind,  rather  than  another  depends 
upon  a  number  of  forces,  which  work  together  with  the  as- 
sociative tendency  in  determining  the  recall. 

The  Goal  Idea.  —  Two  different  theories,  at  present  cur- 
rent, attempt  to  remedy  this  deficiency  in  the  doctrine  of 
association.  One  proposed  by  Aschaffenburg  and  much 
used  by  the  psychiatrists  would  refer  the  determination  of 
the  course  of  ideas  to  the  effect  of  the  final  idea  in  the 


ATTENTION  AND   IDEAS  285 

series,  —  the  goal  idea.  Thus  if  the  goal  of  the  sentence 
is  to  describe  the  weather,  one  set  of  words  will  be  sug- 
gested; if  the  aim  is  to  decline  an  invitation,  another  series 
of  words  may  be  called  out,  even  if  one  start  with  the 
same  word.  When  the  course  of  thought  leads  to  the  goal, 
it  is  said  that  the  goal  idea  dominates  it;  if  it  wanders  at 
random  by  virtue  of  the  strength  of  the  connections  be- 
tween each  pair  of  ideas,  we  have  to  do  with  another  sort 
of  thought.  For  the  diagnosis  of  mental  disease,  thinking 
dominated  by  goal  ideas  is  normal,  while,  when  the  goal 
idea  is  lacking  or  is  of  slight  effect,  one  has  an  indication 
of  mental  abnormality.  There  can  be  no  doubt  that  these 
terms  describe  an  important  difference  between  types  of 
thought,  that  associations  may  be  classified  in  this  way. 
It  is  open  to  objection  in  that  it  gives  merely  a  descriptive 
classification  rather  than  an  indication  of  the  effective 
causes  or  conditions  in  the  course  of  ideas.  One  cannot 
think  of  the  last  idea  in  the  series  as  exerting  an  influence 
upon  those  that  precede  it.  A  force  cannot  be  regarded 
as  exerting  an  influence  before  it  comes  into  being. 

Mechanical  Factors  in  the  Control  of  Association.  —  On 
the  other  theory  the  same  facts  are  taken  into  considera- 
tion, but  the  explanation  is  in  terms  of  determinants  rather 
than  of  goals,  of  antecedent  rather  than  of  consequent 
events.  We  may  take  over  almost  bodily  our  conditions 
of  attention  and  apply  them  to  enumerate  the  factors  that 
determine  the  selection  of  one  possible  associate  from  the 
others.  Corresponding  to  the  objective  conditions,  we  find 
the  factors  that  determine  the  strength  of  the  connection 
between  one  element  and  those  that  have  been  associated 
with  it.  These  have  been  shown  to  be  the  frequency  with 
which  the  two  elements  have  appeared  together,  the  re- 
cency of  their  association,  the  degree  in  which  they  were 


286        FUNDAMENTALS   OF  PSYCHOLOGY 

attended  to  or  the  intensity  of  the  stimuli  that  called  out  a 
response  at  the  time  of  their  earlier  appearance,  and  the 
primacy  of  the  association.  Professor  Calkins  has  shown 
that  the  earlier  one  element  enters  into  an  association  with 
another,  the  more  likely  it  is  to  be  recalled  with  that  than 
with  any  other  with  which  it  has  been  associated  at  a  later 
period.  It  should  be  added  that  Galton  found  that  very 
many  of  the  ideas  in  a  train  came  from  youth.  He  kept  a 
list  of  ideas  that  were  suggested  to  him  by  objects  or 
words,  and  then  traced  them  to  the  time  of  their  original 
experience.  Thirty-nine  per  cent  were  found  to  come  from 
boyhood  and  youth,  46  per  cent  from  the  period  of 
subsequent  manhood,  and  15  per  cent  from  quite  re- 
cent events.  This  indicates  that  impressions  received  in 
youth  are  better  retained  and  are  stronger  in  their  connec- 
tions than  those  received  at  later  times.  This  may  be  said 
to  be  due,  either  to  primacy,  that  is  the  greater  degree  of 
retentiveness  of  the  associations  first  formed,  or  to  the 
greater  interest  in  the  events  of  the  early  period  of  life. 
Professor  Calkins  also  found  that  primacy  was  an  impor- 
tant factor  in  the  determination  of  the  strength  of  asso- 
ciates, even  when  they  were  formed  in  adult  life. 

Intensity  and  Recall.  —  A  number  of  experiments  from 
Ebbinghaus  prove  that  both  the  frequency  .^and  recency  of 
associations  are  important  elements  in  the  determination 
of  the  probability  of  recall.  Intensity  does  not  lend  itself 
so  well  to  experimentation,  but  chance  observation  indi- 
cates that  the  more  intense  stimulations  leave  more  per- 
manent effects.  Under  this  head  come  cases  in  which  the 
intensity  is  of  subjective  origin,  is  due  to  a  strong  feeHng 
or  to  close  attention.  It  has  been  shown  that  the  degree 
of  attention  increases  the  likelihood  of  recall,  and,  while 
the  experimental  case  for  feeling  is  not  so  complete,  there 


ATTENTION  AND   IDEAS  287 

is  good  evidence  from  everyday  life  that  this,  too,  serves  to 
increase  the  closeness  of  the  connection.  As  a  result  of 
these  objective  conditions,  the  tendency  of  any  idea  or  par- 
tially aroused  neurone  to  arouse  some  other  is  constant. 
Furthermore,  were  this  strength  of  connection  the  only 
thing  to  be  taken  into  consideration,  it  would  be  very  dif- 
ficult for  the  connections  to  be  changed.  The  idea  recalled 
by  any  given  idea  would  be  determined  once  and  for  all. 
The  only  way  one  association  could  be  broken  and  another 
substituted  would  be  to  permit  a  long  lapse  of  time  and 
the  formation  of  some  very  strong  new  association.  It 
would  mean,  in  any  mind  subject  to  its  rule,  a  perfect 
mechanism  with  no  possibility  of  breaking  away  from  its 
domination. 

Subjective  Conditions  of  Recall.  —  This  tyranny  of  as- 
sociation is  tempered  by  the  subjective  conditions  of  atten- 
tion which  play  a  part  here,  as  well  as  in  the  entrance  of 
sensations  to  consciousness.  By  far  the  most  important  of 
these  is  to  be  found  in  the  mental  attitude  of  the  moment, 
the  purpose  or  problem  that  is  set  the  individual.  If  one 
be  given  such  a  word  as  dog,  a  very  large  number  of  asso- 
ciates can  readily  be  recalled.  If,  however,  it  is  coupled 
with  the  request  to  name  the  class  to  which  it  belongs,  ver- 
tebrate, anmial,  or  some  other  more  general  term  will  be 
aroused.  While  if  one  is  asked  to  give  a  member  of  the 
class,  a  species  of  dog  or  the  name  of  some  particular  dog 
is  spoken.  There  is  still  room  for  selection  within  the 
group,  but  the  group  itself  is  very  much  narrowed.  Simi- 
larly, if  two  numbers  are  shown  written  one  above  the 

other  and  a  line  drawn  beneath,  as  .,  six,  eighteen,  or 
seventy-two  might  be  associated  with  them.    If  they  ap- 


288        FUNDAMENTALS   OF   PSYCHOLOGY 

pear  in  a  check  book  or  in  other  real  relations,  the  purpose 
and  the  knowledge  of  what  has  gone  before  serve  to  deter- 
mine whether  one  or  another  number  shall  suggest  itself. 
If  the  problem  is  set  by  another,  if  the  sum  appears  in  a 
series  in  which  one  has  been  asked  to  add,  subtract,  or 
multiply,  that  request  will  suffice  to  suggest  the  corre- 
sponding figure.  In  any  case,  either  the  task  that  has  been 
set  by  another,  the  demands  of  the  situation,  or  the  atti- 
tude that  one  may  happen  to  be  in,  will  choose  from  among 
the  possible  associates  the  one  most  suitable.  In  addition 
to  the  setting,  education  and  the  social  influences  that  are 
behind  voluntary  control  of  attention  also  have  an  impor- 
tant part  in  the  guidance  of  ideas.  While  association  pro- 
vides the  possible  paths  along  which  ideas  may  flow,  these 
possibiKties  are  made  actuahties  by  the  more  subjective 
conditions  derived  from  the  earUer  experience  and  present 
intentions  of  the  individual,  and  the  necessities  that  bear 
upon  him  at  the  moment.  AH  the  factors  that  control  at- 
tention serve  also  to  select  the  associates. 

Forms  of  Attention 

Three  Forms  of  Attention.  —  It  is  customary  to  di\ide 
attention,  whether  apphed  to  external  objects  or  to  the  con- 
trol of  ideas,  into  three  groups,  —  voluntary,  involuntary, 
and  non-voluntary.  In  popular  terms  the  basis  of  division  is 
with  reference  to  the  presence  or  absence  of  the  will.  As 
we  do  not  care  to  raise  the  question  of  the  wiU  at  the  pres- 
ent time,  we  can  make  the  classification  with  reference  to 
the  conditions  and  characteristics  of  the  attention  process 
discussed  above. 

Involuntary  Attention.  —  In  general,  it  can  be  seen  that 
the  attention  called  involuntary  corresponds  to  attention 
that  is  determined  altogether  by  the  objective  factors.    We 


FORMS   OF  ATTENTION  289 

attend  in  spite  of  ourselves  because  the  stimulus  is  strong 
enough  to  force  itself  into  consciousness,  whatever  the 
state  of  consciousness  itself  may  be  at  the  moment.  At- 
tending is  against  the  will,  against  the  desire  of  the  indi- 
vidual at  the  moment.  We  desire  to  read,  and  the  noises 
of  the  street  force  themselves  upon  us,  or  we  desire  to  re- 
call the  book  in  which  a  certain  statement  was  made,  and 
a  large  number  of  ideas  keep  forcing  themselves  upon  us. 
In  the  latter  case  the  associations  of  irrelevant  things  are 
so  strong  that  the  relevant  idea  is  kept  out. 

Voluntary  Allenlion  and  ^^or/.  —  Voluntary  attention, 
on  the  other  hand,  is  that  which  is  determined  by  social 
pressure.  The  desire  to  attend  is  not  one  that  springs 
spontaneously,  but  is  due  to  the  impulsion  of  some  remote 
end.  In  most  cases,  a  struggle  between  the  immediate  and 
the  remote  good  or  pleasure  is  involved.  Usually,  too,  as 
has  been  said,  the  remote  good  is  impressed  upon  us  by 
some  form  of  social  pressure.  The  approval  of  some  part 
of  the  immediate  social  group  is  necessary  to  make  the 
distant  goal  more  attractive  than  the  inherently  pleasant 
processes  that  would  lead  us  away  from  it.  In  this  sense 
social  pressure  is  the  real  motive  force  behind  attention, 
the  force  that  holds  the  individual  to  the  less  pleasant  in 
the  face  of  the  more  pleasant.  The  characteristic  conscious 
accompaniment  of  voluntary  attention  is  a  mass  of  strain 
sensations,  sensations  which,  taken  together,  constitute  the 
feeling  of  effort.  As  was  said  in  the  discussion  of  the  motor 
accompaniments  of  attention,  all  attention  involving  con- 
flict of  motives  tends  to  arouse  diffuse  contractions  in  a 
number  of  muscles,  contractions  which  are  in  themselves 
of  no  great  effect  upon  the  attention  process,  but  which 
are  accepted  as  an  indication  that  some  force  is  active. 
They  make  us  feel  active,  are  said  to  constitute  a  sign  of 


290        FUNDAMENTALS   OF  PSYCHOLOGY 

the  activity  of  the  will.  So  far  as  we  now  know,  they  are 
not  a  cause  but  an  effect,  they  are  a  sign,  not  of  a  new 
force,  but  of  a  conflict  of  conditions.  That  they  have  no 
good  effect  is  evident  from  the  fact  that  they  do  not  ac- 
company the  most  effective  attention  and,  when  they  ap- 
pear, usually  die  away  as  soon  as  the  highest  stage  of  effi- 
ciency of  attention  is  attained.  Voluntary  attention  is  due 
to  social  pressure  and  is  accompanied  by  strain  sensations. 
All  strain  sensations  taken  together  constitute  what  we  call 
the  feeling  of  effort. 

Non-voluntary  Attention  and  Interest. — The  non-vol- 
untary form  of  attention  includes  all  classes  not  previously 
covered.  The  more  important  conditions  are  the  mental 
attitude  of  the  moment,  the  momentary  purpose,  educa- 
tion, and  heredity  or  instinct.  These  seem  to  induce  at- 
tention in  accordance  with  the  momentary  nature  of  the 
individual;  they  constitute  in  sum  total  the  conditions  of 
desire.  The  characteristic  accompaniment  of  this  form  of 
attention  is  interest,  a  feehng  of  pleasure  due  to  the  lack 
of  conflict.  In  so  far  as  it  is  strictly  interest,  it  is  a  pleas- 
ure derived  from  the  mere  act  of  attending,  rather  than 
from  the  nature  of  the  thing  attended  to.  Why  it  should 
come  or  how  it  originates  need  not  concern  us  here;  in 
fact,  no  satisfactory  explanation  has  been  given  for  it.  It 
is  essential  to  emphasize  that  both  interest  and  the  feehng 
of  effort  are  accompaniments  or  effects,  not  causes.  After 
all,  then,  these  three  divisions  of  attention  are  not  entirely 
distinct.  All  forms  produce  the  same  effects  in  conscious- 
ness; they  are  distinct  only  in  that  in  certain  cases  the 
sensations  of  effort  or  the  feeling  of  interest  accompany 
them;  they  gradually  shade  over  into  each  other  without 
sharp  Une  of  division.    Attention  is  a  unitary  process. 


PHYSIOLOGICAL  THEORIES  OF  ATTENTION    291 

The  Physiological  Basis  of  Attention 

The  Physiological  Explanation  of  Attention.  —  On  its 
physiological  or  nervous  side,  attention  may  best  be  pic- 
tured as  a  preparation  of  one  tract  or  set  of  tracts  for  action. 
The  nature  of  this  preparation  in  advance  of  the  entrance 
of  an  idea  varies  for  the  different  subjective  conditions. 
The  immediately  preceding  stimulus  and  the  idea  in  mind 
can  be  pictured  as  due  to  the  effect  of  a  previous  stimula- 
tion of  the  same  tracts,  which  in  consequence  are  still  par- 
tially active  at  the  moment  the  new  excitation  is  received. 
This  corresponds  to  the  fact  noted  in  the  preceding  chapter 
that  the  nervous  response  continues  for  several  seconds  in 
relatively  high  degree  and  probably  for  a  considerably  longer 
time  in  some  degree.  The  entering  stimulus,  finding  these 
tracts  already  active,  produces  a  greater  excitation  than  it 
otherwise  would  or,  if  several  stimuli  of  approximately 
equal  intensity  are  presenting  themselves,  that  one  produces 
its  effect  for  which  the  way  has  been  prepared  by  this 
partial  excitation. 

Attention  as  Facilitation  and  Inhibition.  —  The  influence 
of  attitude  or  purpose  is  the  result  of  the  spreading  to  a 
large  number  of  associated  paths  of  the  impulse  developed 
by  the  stimulus  which  arouses  the  attitude.  One  may 
think  of  the  interaction  of  different  parts  of  the  cortex 
during  attention  as  the  effect  of  a  widened  associa- 
tion. As  was  said  in  the  fifth  chapter  the  excitation  of  a 
neurone  not  merely  arouses  those  neurones  which  specifi- 
cally excite  movements  or  are  accompanied  by  overt  con- 
sciousness, but  it  also  exerts  a  tendency  to  arouse  certain 
neurones  and  to  suppress  the  activity  of  others.  When  one 
is  asked  a  question,  the  question,  by  association,  tends  to 
arouse  the  possible  answers.    This  means  that  the  impulse 


292        FUNDAMENTALS   OF  PSYCHOLOGY 

spreads  from  the  auditory  neurones  that  receive  the  ques- 
tion to  the  others  associated  with  it  in  previous  experience. 
In  addition,  it  would  increase  the  tendency  to  activity  in 
a  number  of  other  neurones  related  to  the  first,  and  would 
probably  check  the  activity  of  others  which  were  not  con- 
nected with  the  first.  This  would  make  it  very  likely  that 
any  stimulus  that  afTects  any  of  the  prepared  neurones 
would  be  appreciated,  while  all  other  stimuH  would  be 
less  likely  to  be  noticed  than  they  would  be  if  there  had 
been  no  preliminary  preparation.  An  attitude  has  a  similar 
effect.  When  in  a  biological  laboratory,  the  parts  of  the 
cortex  that  have  received  stimulation  in  connection  with 
the  observation  of  animals  are  partially  active  or  are  at 
least  prepared  for  activity,  while  other  neurones  are  ren- 
dered less  likely  to  respond. 

The  effect  of  education  is  to  prepare  these  systems  of 
paths  so  that  they  may  be  excited  by  the  particular  stimuli 
or  the  particular  occasions.  It  is  essentially  a  process  of 
organizing  cerebral  cells  into  groups  so  that  one  entire  group, 
as  well  as  some  particular  associate,  may  be  aroused  or 
partially  aroused  by  a  suitable  stimulus.  Each  of  these 
processes  may  be  regarded  as  an  explanation  of  the  selec- 
tion, either  from  among  the  stimuli  which  seek  to  enter 
consciousness,  or  between  ideas  that  are  associated  with 
the  particular  idea  that  serves  as  excitant.  Thus  on  the 
nervous  side,  the  course  of  impulses  is  determined  by  the 
action  of  very  large  numbers  of  neurones,  many  of  them 
very  remote  from  the  neurones  which  are  actually  the  seat 
of  the  processes  attended  to.  The  cortex  acts  as  a  unit 
rather  than  in  parts,  just  as,  on  the  side  of  consciousness, 
practically  all  experience  unites  in  determining  the  course 
of  any  single  element  of  consciousness. 


PHYSIOLOGICAL  THEORIES  OF  ATTENTION     293 

REFERENCES 

Pillsbury:   Attention. 

Titchener:   Lectures    on     the    Psychology    of    Feeling    and 

Attention. 
Morgan:  On  Overcoming  Distraction.    Archives  of  Psychology, 

No.  35. 


CHAPTER  X 
PERCEPTION 

General  Remarks 

Perception  may  be  defined  as  the  process  of  becoming 
aware  of  an  object.  A  perception  is  different  from  sensa- 
tion in  that  it  is  the  appreciation  of  an  object  as  an  object, 
while  a  sensation  is  not  known  for  itself  or  at  least  by  itself, 
but  is  always  a  part  of  something  else  from  which  it  is 
abstracted.  The  perception  always  is  initiated  by  some 
sensation.  It  begins  with  the  stimulation  of  some  one  of  the 
senses.  But  as  a  result  of  that  stimulation  we  add  to  the 
sensation  a  mental  construction  or  series  of  mental  processes 
which  result  in  giving  us  the  impression  of  a  whole  object. 

Perception  a  Process  of  Association.  —  The  additions  are 
of  at  least  three  kinds.  In  the  first  place,  one  sensation 
may  fuse  with  others  from  the  same  or  different  senses. 
This  is  our  experience  when  we  see  an  object  and  touch  it 
at  the  same  time.  The  two  impressions  combine  to  form  a 
single  or  common  process. 

More  frequent  and  more  important  is  the  second  instance 
—  the  addition  of  memory  images.  When  an  object  has 
been  seen  and  touched  at  the  same  time  on  various  occa- 
sions, we  have  the  formation  of  association  processes  which 
makes  us  recall  the  image  of  the  object  when  it  is  touched 
and  also  recall  the  sensations  of  touch,  that  we  had  received 
earUer,  when  the  object  is  seen.  Supplementing  by  memories 
or  centrally  aroused  impressions  is  most  frequent  and  most 
prominent  among  the  elements  in  perceptions.  We  are 
294 


PERCEPTION  295 

constantly  being  led  on  from  the  sense  impressions  them- 
selves to  recalled  or  added  memories.  Our  perceptions  are 
mosaics  of  sensations  and  memories  in  which  we  do  not 
distinguish  one  from  the  other.  In  filling  the  blind  spot, 
for  example,  we  add,  to  the  sensations  received  from  the 
retina  surrounding  the  blind  spot,  imagined  processes  sug- 
gested by  them,  and  do  not  notice  where  the  actual  sensa- 
tions cease  and  remembered  impressions  begin.  In  all 
other  senses  we  make  similar  additions  which  fuse  with  the 
sensations  into  a  uniform  whole  which  cannot  be  analyzed 
into  parts.  A  perception  is  a  fusion  of  sensation  and  memo- 
ries in  which  sensation  and  memory  are  indistinguishable. 
Perception  Involves  Wide  Correction  of  Experiences.  — 
In  the  third  place  we  find  that  the  object  recalled  is  usually 
corrected  in  ways  that  go  beyond  the  mere  addition  of  mem- 
ories. The  object  which  we  perceive  is  always  regarded  as 
existing  in  the  outside  world,  and  that  object  is  seen  as 
we  beheve  it  must  exist  in  the  outside  world.  In  many 
cases  the  object,  as  we  think  it.  is  not  as  we  could  have  seen 
it  at  any  time  in  the  past.  The  corrections  could  not  be 
made  by  referring  from  the  present  group  of  sensations 
to  a  group  that  might  have  been  received  at  any  single 
earlier  time.  In  addition  we  change  the  interpretation  in 
an  indefinite  way  to  correspond  to  a  number  of  different 
experiences  of  the  object.  We  tend  to  see  an  object  as  we 
know  it  must  be  on  the  basis  of  all  the  experiences  that  we 
have  had  of  it,  rather  than  by  correcting  a  single  impression 
of  the  present  in  terms  of  a  single  experience  of  the  past. 
In  the  interpretation  we  replace  the  group  of  experiences 
actually  presented  by  another  group  that  seems  to  us  to  be 
more  in  harmony  with  everything  that  we  know.  The 
simplest  illustration  that  can  be  given  is  the  way  in  which 
we  see  the  top  of  a  table  or  other  rectangular  surface.    It 


296        FUNDAMENTALS   OF  PSYCHOLOGY 

is  on  the  retina  a  figure  with  the  front  and  back  sides 
approximately  parallel  but  with  the  other  two  sides  slanting 
towards  each  other  and  usually  making  obtuse  and  acute 
angles  with  the  front.  This  figure  is  almost  always  finally 
interpreted  as  a  rectangle.  We  could  never  see  the  figure 
in  such  a  way  as  to  give  this  impression.  The  nearest 
approach  to  it  is  if  we  should  have  one  eye  directly  over  it. 
Even  then  the  sides  would  not  be  straight  lines  but  would 
be  bent  because  they  are  received  upon  the  curved  surface 
of  the  retina.  This  figure  with  which  we  replace  the  rec- 
tangle is  something  that  we  know  from  all  of  our  experience 
must  be  the  object  as  it  exists  in  the  outside  world,  but  it  is 
not  known  to  exist  in  that  form  because  it  has  never  been 
seen  in  just  that  shape;  however,  when  we  test  it  by  building 
it  or  by  fitting  it  into  corners  that  we  know  are  square,  it 
proves  to  be  rectangular.  In  other  words  we  accept  as 
real  the  construction  that  has  proved  on  earher  test  to 
harmonize  with  all  of  our  experiences  of  that  object.  We 
see  and  hear  by  replacing  or  correcting  our  sensations  as 
our  experience  proves  that  we  must  correct  them  if  they 
are  to  explain  the  world  as  we  have  known  it.  It  is  little 
more  than  fair  to  say  that  we  see  these  corrected  concepts 
rather  than  actual  sensations,  or  than  mere  combinations 
of  sensations  and  memories,  although  both  sensations  and 
memories  are  the  all  important  components  of  the  per- 
ceptions. Instances  in  which  we  see  these  corrected  and 
harmonized  results  of  past  experiences  will  be  found  to  be 
numerous  in  our  discussion  of  perception. 

Perception  Implies  Movement.  —  These  corrections  in 
the  fight  of  wider  experiences  always  involve  a  considerable 
amount  of  reference  to  action.  The  tests  that  we  apply 
to  the  objects  are  frequently  of  a  type  to  involve  action. 
We  know  what  objects  are  like  because  we  try  to  manipu- 


PERCEPTION  297 

late  them  in  various  ways.  One  may  go  farther  and  argue 
that,  since  to  every  sensation  there  is  some  form  of  motor 
response,  perception,  too,  must  involve  some  motor  activi- 
ties, and  that  these  motor  responses  are  an  essential 
part  of  our  interpretation  of  the  object.  The  behaviorists 
would  go  so  far  as  to  add  that  all  that  there  is  of  impor- 
tance in  the  percept  is  this  reaction  or  group  of  reactions. 
Since  their  theory  leaves  Httle  room  for  knowledge,  it 
makes  relatively  slight  difference  to  them  whether  we  per- 
ceive through  our  movements  or  not.  One  must  insist  that 
response  to  movements  modifies  our  knowledge  and  that 
the  nature  of  the  responses  is  an  element  that  cannot  be 
neglected  in  a  discussion  of  perception,  although  it  is  not 
always  possible,  in  fact  has  seldom  been  possible,  to  detect 
the  elements  that  movement  adds  to  the  perception  in 
individual  cases. 

Percepts  are  always  Things.  —  A  fourth  fact  that  must 
be  kept  in  mind  is  that  we  always  think  of  the  product  of 
the  process  that  gives  rise  to  perception  as  something  in 
the  outside  world  rather  than  as  a  mere  combination  of 
mental  processes.  This  hardly  needs  to  be  added  from  the 
standpoint  of  common  sense  because  everything  that  is 
thought  of  at  all  is  thought  of  as  having  real  existence,  as 
being  part  of  the  real  external  world.  Still  it  is  an  important 
fact  that  as  we  receive  a  sensation  from  the  retina  we  never 
think  of  referring  it  to  the  retina  alone,  but  always  regard 
it  as  an  object.  So  direct  and  complete  is  this  reference 
that  we  do  not  first  receive  the  impression  with  the  notion 
that  it  might  be  a  mere  image  on  the  retina  and  then  decide 
to  refer  it  to  a  certain  distance  in  the  outside  space.  The 
reference  is  immediate.  The  correct  construction  is  seen 
at  once  as  an  object  at  a  certain  distance,  without  any  inter- 
vening activity  of  thought.    The  mental  process  is  made  to 


298        FUNDAMENTALS   OF  PSYCHOLOGY 

mean  an  object  in  the  outside  world,  and  we  are  aware  of 
the  meaning  alone.  We  know  nothing  of  the  group  of  sen- 
sations and  images  which  must  be  the  mental  occasion  for 
the  development  of  the  meaning.  The  matter  might  be 
put  more  definitely  by  saying  that  certain  sensations  have 
come  to  stand  for  an  object  in  the  outside  world;  and 
that  we  now  accept  the  sensations  that  come  in,  as  a  sign 
that  the  object  is  present  in  the  world  without.  But  in  all 
this,  it  should  be  emphasized  that  what  we  are  immediately 
aware  of  is  always  the  object  that  is  meant  and  for  which 
we  have  the  sign,  rather  than  the  sensations  or  the  signs 
themselves.  These  various  steps  and  aspects  of  the  develop- 
ment of  perceptions  we  shall  have  occasion  to  indicate  at 
each  step  in  the  examination  of  the  concrete  perception 
process. 

In  discussing  perception  we  find  it  convenient  to  consider 
certain  of  the  general  aspects  of  objects  first  and  then  pro- 
ceed to  the  more  concrete  phases  later.  All  experiences 
have  duration,  and  we  in  practice  abstract  these  temporal 
phases  from  the  particular  happenings,  and  consider  them 
apart  from  the  events.  We  may  conveniently  discuss  the 
perception  of  time  with  no  reference  to  the  filhng  of  time. 
Space  also  is  involved  in  the  perception  of  all  objects  and 
can  be  discussed  without  reference  to  the  particular  objects 
in  space.  Other  general  aspects  of  experience  are  motion 
and  rhythm.  Each  of  these  can  be  treated  apart  from  its 
particular  content  and  this  simplifies  the  treatment  of  the 
perception  of  particular  objects.  We  may  begin  with  the 
discussion  of  space. 

Perception  of  Space 

Problems  Concerning  Space.  —  Space  is  appreciated  by 
means  of  at  least  four  senses,  —  touch,  vision,  audition, 


PERCEPTION  299 

and  the  kin  aesthetic  sense.  Of  these,  vision  gives  the  most 
accurate  and  complete  appreciation,  touch  combined  with 
the  kina^sthetic  impressions  stands  next  in  definiteness, 
and  the  auditory  space  comes  last.  In  actual  practice  all 
objects  that  are  recognized  as  objects  are  thought  of  as  ex- 
isting in  space,  whether  they  are  actually  sensed  or  merely 
recalled.  In  the  senses  not  mentioned,  the  spatial  aspects 
are  ascribed  to  one  of  the  more  definitely  spatial  senses; 
thus  tastes  are  referred  to  the  tactual  impressions  also  re- 
ceived from  the  tongue,  —  or  are  somewhat  indefinitely 
referred  to  space  in  general.  Odors  are  usually  ascribed  to 
objects,  but  the  localization  is  always  uncertain  and  the 
quaUty  may  be  thought  of  as  independent  of  the  organ,  as 
general  or  all  pervasive.  Not  only  are  the  subordinate 
sensations  referred  to  sight,  but  there  is  much  cross  refer- 
ence between  the  higher  senses.  Different  senses  predomi- 
nate in  different  individuals,  but  in  all  space  interpreta- 
tions several  senses  are  involved. 

Three  different  complexities  of  the  space  problem  pre- 
sent themselves,  although  for  sight  and  kinaesthetic  impres- 
sions alone  are  all  these  problems  to  be  considered.  These 
three  are  the  appreciation  of  position,  of  extent  in  two  dimen- 
sions, and  of  distance  or  depth,  the  third  dimension.  The 
skin  appreciates  position  and  extent  alone;  the  ear,  dis- 
tance and  direction  alone.  We  can  start  with  the  simplest 
problem  in  each  sense  and  transfer  what  may  be  gained 
from  that  to  the  more  complicated  constructions. 

Perception  of  Tactual  Space.  —  Theoretically  simplest  of 
the  space  problems  is  the  appreciation  of  the  position  of  a 
point  upon  the  skin.  Experiments  have  frequently  been 
made  to  determine  how  accurately  a  spot  upon  the  skin 
may  be  locaUzed.  If  one  attempt  to  touch  a  spot  on  the 
skin,  one  will  make  an  error  that  averages  a  centimetre  or 


300        FUNDAMENTALS   OF  PSYCHOLOGY 

so  on  the  wrist  or  on  the  back  of  the  hand,  is  smaller  on 
the  fingers,  and  considerably  larger  on  the  portions  of  the 
body  ordinarily  covered.  This  simple  experiment  indicates 
two  facts:  first,  that  there  must  be  some  way  of  knowing 
where  the  point  touched  is  and  that  this  guides  the  move- 
ment; and  secondly,  that  this  localization  is  not  absolute, 
that  it  is  subject  to  error,  and  more  or  less  variable.  One 
of  the  first  theoretical  attempts  to  determine  what  it  is 
that  gives  a  knowledge  of  position  was  made  by  Lotze. 
Lotze  pictured  the  self  as  somewhere  in  the  brain  and  as 
receiving  impressions  over  the  nerves  from  the  surface  of 
the  body.  Such  a  self  might  be  thought  of  as  constantly 
questioning  what  part  of  the  skin  gives  rise  to  the  sensa- 
tions it  received  and  seeking  for  signs  that  indicate  their 
origin.  Lotze  asserted  that  the  sensations  received  from 
different  parts  of  the  skin  had  different  qualities.  These 
different  qualities  were  not  described  very  definitely,  but 
apparently  were  due  in  part  to  the  character  of  the  skin 
and  the  amount  of  tissue  that  lay  between  it  and  the  bone. 
The  quality  of  any  spot  on  the  skin  he  called  its  'local 
sign.'  If  you  will  try  to  discover  this  local  sign  in  the  sen- 
sations from  your  own  skin,  you  will  find  it  very  difficult. 
Careful  examination  of  the  sensations  fails  to  disclose  any 
such  quality  in  addition  to  the  ordinary  skin  sensations,  — 
one  knows  immediately  where  the  touch  is  but  does  not 
know  how  he  knows. 

Indirect  methods  of  analyzing  the  local  signs  or  means  of 
localization  indicate  that  it  is  dependent  in  part  upon  the 
nerve  stimulated.  When  a  member  has  been  amputated, 
the  sensations  from  the  stump  are  still  referred  to  the  miss- 
ing part,  and  when  a  portion  of  the  skin  has  been  displaced 
by  a  surgical  operation  without  severing  the  nerves  that 
supply  it,  sensations  from  the  skin  will  for  a  time  be  given 


PERCEPTION   OF   POSITION  301 

the  old  position.  It  is  true,  too,  that  the  accuracy  of  lo- 
calization is  greatest  where  the  nerve  endings  are  most 
numerous.  These  factors  might  be  explained  on  Lotze's 
assumption  that  each  nerve  had  a  'local  sign.'  They  also 
have  been  interpreted  to  mean  that  localization  is  due  to 
the  movements  called  out  reflexly.  If  each  point  on  the 
skin  were  connected  with  a  set  of  motor  neurones  that 
would  cause  the  hand  to  move  to  the  point  touched  or  that 
would  call  out  a  slight  movement  toward  the  point,  the 
movement  might  be  used  as  a  sign  of  the  position.  This 
motor  theory  receives  some  support  from  the  fact  that 
animals  whose  brains  have  been  removed,  and  men  in 
their  sleep,  will  touch  the  point  stimulated  with  a  fair  de- 
gree of  accuracy.  That  it  alone  is  not  sufficient  is  prob- 
able from  the  fact  that  the  normal  animal  makes  the  move- 
ment with  greater  accuracy.  Still  a  third  theory  would 
make  the  locaUzation  due  to  the  association  of  other  sen- 
sations with  cutaneous  excitation.  Often  a  picture  of  the 
point  touched  comes  immediately  upon  contact.  However, 
no  one  of  these  theories  may  be  regarded  as  sufficient  in 
itself.  Rather  must  we  assume  that  all  have  acted  to- 
gether to  give  a  notion  of  each  different  position  on  the 
skin.  As  different  points  have  been  touched,  the  kinaes- 
thetic  have  been  associated  with  the  visual  sensations,  and 
these  with  the  sensations  of  contact  and  with  any  other  im- 
pressions that  may  be  concerned.  After  the  notion  has 
been  developed  it  is  called  up  by  any  contact. 

The  'Limen  of  Two-ness.'  —  Much  the  same  problem 
meets  us  in  connection  with  the  appreciation  of  a  minimal 
extent.  This  has  been  studied  by  determining  the  least 
distance  at  which  two  points  might  be  appreciated  as  two. 
Weber,  who  made  the  first  experiments,  found  that  this 
distance  varied  from  approximately  i  mm.  on  the  finger 


302 


FUNDAMENTALS  OF   PSYCHOLOGY 


tips  and  tip  of  the  tongue  to  40-60  mm.  on  the  middle  of 
the  back.  In  general  it  was  larger  on  the  portions  of  the 
body  ordinarily  covered  and,  on  the  limbs,  decreased  regu- 
larly from  the  centre  of  rotation  downward.  Volkmann 
noted  that  it  varies  approximately  with  the  amount  of 
motion  of  the  member  and  of  the  parts  of  the  member  in 
question.  Goldscheider  repeated  the  experiments  by  put- 
ting the  points  of  a  compass  upon  pressure  spots,  and 
found  that  two  points  might  be  distinguished  when  the 
points  were  on  contiguous  spots.  His  values  varied  from 
0.3-0.6  mm.  on  tongue  and  finger  tip  to  4-6  mm.  on  the 
back.  Later  experiments  by  von  Frey  indicated  that  these 
values  were  too  small  unless  the  stimuH  were  appKed  suc- 
cessively. In  these  experiments,  as  in  comparisons  in  gen- 
eral, successive  stimuH  are  judged  more  accurately  than 
simultaneous  stimuH.  It  is  also  to  be  noted  that  practice 
and  suggestion  have  marked  effects.  Values  may  be  re- 
duced one-half  or  more  in  a  few  weeks'  practice.  It  is 
seen,  too,  that  practice  on  one  part  of  the  body  will  have 
an  effect  upon  the  symmetrical  areas  that  have  not  them- 
selves been  exercised. 

The  explanation  of  these  values  may  be  reduced  in  part 
to  a  matter  of  comparing  'local  signs.'  When  two  signs  of 
position  are  much  alike,  they  are  confused  and  made  to 
constitute  one  point.  By  sign  of  position  may  be  meant, 
either  the  actual  sensory  qualities  received  from  the  points, 
if  they  exist,  or  the  movements  that  must  be  made  to 
touch  each,  or  the  suggested  motion  from  one  to  the  other, 
or  reference  to  visual  distances.  Improvement  with  prac- 
tice is  suggestive  of  this  process  of  analysis,  as  is  also  the 
greater  acuity  on  the  more  mobile  and  in  consequence  more 
frequently  used  members.  Larger  extents  probably  de- 
pend more  upon  movement  from  one  point  to  the  other, 


PERCEPTION  OF  VISUAL   SPACE  303 

either  of  the  member  itself  or  of  another  exploring  organ. 
A  curious  illusion  that  arises  in  the  comparison  of  filled 
with  empty  space  would  indicate  that  the  nature  of  the 
stimulation  plays  a  part.  If  one  is  asked  to  compare  a  sin- 
gle empty  space  with  a  space  containing  other  stimulated 
points,  the  empty  space  seems  greater  than  the  interrupted 
space.  The  explanation  is  difficult  in  terms  either  of 
movement  or  analysis.  The  importance  of  reference  to 
vision  should  also  be  emphasized.  Many  individuals  trans- 
late cutaneous  sensations  into  vision,  and  do  not  appre- 
ciate the  distance  until  this  translation  is  complete.  This 
statement  may  be  verified  if  one  will  have  another  trace 
outlines  on  the  skin,  or  press  objects  of  different  shapes 
against  it.  The  bhnd  must  of  course  have  an  immediate 
appreciation  in  terms  of  pure  cutaneous  impressions  or  of 
movements.  How  these  different  factors  cooperate  is  not 
as  yet  known,  but  it  is  undoubtedly  a  process  that  is  much 
more  complicated  than  the  simple  theories  we  have  indi- 
cated would  seem  to  imply. 

Retinal  Local  Sign.  —  If  one  is  to  explain  something  of 
the  spatial  perception  on  the  skin  by  reference  to  the  in- 
fluence of  vision,  it  is  also  necessary  to  understand  how  po- 
sition and  extent  may  be  perceived  on  the  retina.  The 
same  problems  meet  us  here  and  many  of  the  same  facts 
are  present  to  provide  the  data  for  discussion.  There  is  a 
lower  limit  of  distance  that  must  separate  two  points  if 
they  are  to  be  perceived  as  two.  On  the  fovea  if  two  dots 
or  fines  are  nearer  together  than  .004-. 006  mm.,  or  an  an- 
gular distance  of  6o"-9o",  they  fuse  into  a  single  fine  or 
dot.  This  may  be  regarded  as  the  'fimen  of  two-ness'  for 
sigfit.  The  effects  of  the  inabifity  to  distinguish  fines  and 
points  closer  together  than  this  minimum  can  be  seen  in 
the  abifity  to  distinguish  letters  in  reading.     The  normal 


304        FUNDAMENTALS   OF  PSYCHOLOGY 

eye  can  read  letters  when  the  width  of  the  separate  Unes 
and  the  distances  that  separate  them  are  each  i'.  The 
Snellen  types  in  the  adjoining  figure  can  be  read  at  a  dis- 
tance such  that  the  hues  are  separated  by  this  amount  or 
by  .004  mm.  on  the  retina.  Stratton  found  that  if  two 
vertical  Knes  placed  one  above  the  other  were  brought  to- 
gether at  their  extremities,  a  break  in  the  Kne  could  be 
noted  when  they  were  displaced  7"  only.  In  this  case, 
however,  the  difference  in  direction  of  the  hues  probably 
■  "^  B^H  BMiV  ^^^°  gives  a  cue;  it  is  not 
pj^  flJ  t'¥^'\  "merely  appreciation  of  the  dis- 
■Bfl  ■;..  ■  ^gg|g  tance  between  points.  As  the 
iG.  71.—  ne  en  types.  distance    that    separates    the 

centres  of  cones  in  the  fovea  is  only  about  4o"-6o",  it 
would  seem  that  stimuli  no  farther  apart  than  the  centres 
of  neighboring  cones  can  be  discriminated.  As  one  pro- 
ceeds outward  from  the  fovea,  the  acuity  diminishes  very 
rapidly.  Five  degrees  from  the  centre  it  has  been  reduced 
to  one-fourth  and  at  forty  degrees  to  one  two-hundredth  of 
the  maximum  value.  In  twihght  vision,  where  the  cones 
are  not  involved,  acuity  is  approximately  the  same  in  all 
portions  of  the  field  beyond  ten  degrees  from  the  centre. 
It  is  zero  in  the  fovea  itself,  and  rises  very  rapidly  to  at- 
tain a  constant  value  five  to  ten  degrees  distant. 

The  theories  of  the  appreciation  of  position  and  extent 
upon  the  retina  involve  the  same  principles  as  those  ad- 
vanced for  the  skin.  The  awareness  of  position  seems  to 
depend  in  some  way  upon  the  nerve  element  stimulated, 
as  is  evidenced  by  the  fact  that  when  a  retinal  element  is 
displaced  it  still  gives  the  old  sign  of  position.  Thus  Wundt 
at  one  time  suffered  from  choroiditis  under  one  small  portion 
of  the  retina.  This  caused  a  swelhng  of  the  retina  and  finally 
resulted  in  a  small  scotoma  or  blind  spot.  While  the  elements 


PERCEPTION  OF  VISUAL   SPACE  305 

of  the  retina  were  displaced  in  this  region,  the  straight  Hnes 
seen  on  it  were  distorted,  and  it  was  only  after  the  rods  and 
cones  had  been  used  in  their  new  positions  for  a  consider- 
able time  that  the  spatial  relations  became  normal  again. 

Theories  of  Localization  —  This  sign  of  position  that  at- 
taches to  the  retinal  element  has  been  ascribed  to  the  con- 
jectural 'local  sign'  and  to  movement.  Differences  in  the 
quahties  of  sensations  received  on  different  areas  of  the 
retina  have  been  suggested  as  furnishing  the  means  of  dis- 
tinguishing position.  Even  the  difference  in  the  quahty  of 
a  color  has  been  suggested  as  a  sign.  In  the  movement 
theory  it  is  assumed  that  the  tendency  of  the  eye  to  turn 
in  such  a  way  that  the  point  attended  to  shall  fall  upon  the 
fovea  constitutes  the  mark  of  position.  The  more  general 
and  inclusive  the  final  explanation,  the  greater  the  likeli- 
hood that  it  will  be  correct.  It  is  probable  that  the  idea 
of  position  here,  too,  is  a  notion  that  has  been  gradually 
developed  through  experience  of  all  possible  sorts,  that  it 
includes  reference  to  motion,  to  areas  as  known  on  the 
skin,  and  particularly  to  the  movement  of  the  fingers  over 
surfaces  as  eye  and  finger  explore  them  together,  and  a 
large  number  of  more  general  practical  tests.  After  the 
complex  idea  has  developed,  some  peculiarity  in  the  retinal 
element  stimulated  or  the  activities  aroused  by  the  stimu- 
lation suggest  this  idea  or  concept.  Either  such  a  highly 
complex  concept  of  position  whose  origin  has  been  lost  in 
the  course  of  its  development,  and  which  is  now  appre- 
ciated only  for  its  meaning,  must  be  assumed  to  constitute 
our  idea  of  position,  or  we  must  leave  the  problem  unsolved. 

The  perception  of  greater  visual  extents  depends  very 
largely  upon  the  eye  movements.  This  phase  of  perception 
has  been  investigated  with  more  care  for  the  eye  than  for 
the  skin.    Studies  in  the  comparison  of  two  Unes  show  that 


3o6        FUNDAMENTALS   OF  PSYCHOLOGY 

the  appreciation  of  distance  follows  Weber's  law,  —  one 
can  appreciate  an  addition  in  length  of  from  iV  to  eV  to  a 
horizontal  line,  an  average  of  about  sV-  Appreciation  of 
difference  in  the  length  of  vertical  lines  is  slightly  less  ac- 
curate, an  average  of  about  -rs.  This  shghter  degree  of 
accuracy  in  perception  of  vertical  movements  has  been 
connected  with  the  fact  that  the  vertical  movements  re- 
quire two  pairs  of  muscles  and  so  a  greater  amount  of  ef- 
fort than  horizontal  movements.    They  are  thus  less  accu- 


FiG.  72.  — Muscles  of  the  eye.  rs,  superior  rectus;  rij,  rectus  inferior;  re,  ex- 
ternal rectus;  rit,  rectus  internus;  os,  superior  oblique;  oi,  inferior  oblique;  /,  ten- 
don of  superior  oblique  which  runs  through  the  membranous  pulley,  u,  on  nasal 
wall  of  the  socket. 

rate  and  more  difficult  to  compare.  As  one  estimates  the 
length  of  a  line,  the  eyes  move  from  one  end  to  the  other 
and  the  comparison  is  probably  very  largely  through  these 
movements.  The  qualitative  characteristics  or  group  of 
'local  signs'  may  also  be  involved;  biit  here,  as  in  the  Hmi- 
nal  values,  they  have  not  been  clearly  discriminated. 

The  Eye  Muscles.  —  The  importance  of  eye  movement 
in  the  perception  of  space  makes  it  desirable  to  give  a  brief 
statement  of  the  muscular  mechanism.  The  eye  is  moved 
by  six  muscles  arranged  in  pairs,  and  named,  from  func- 


PERCEPTION  OF  VISUAL  SPACE  307 

tions  and  attachments,  the  internal  and  external  recti,  the 
inferior  and  superior  recti,  and  the  inferior  and  superior 
oblique.  The  recti  muscles  all  spring  from  near  the  apex 
of  the  eye  socket  and  pass  directly  forward  to  their  point 
of  attachment  on  the  surface  of  the  eyeball.  The  superior 
obKque  also  originates  at  the  apex  but  runs  forward  to  a 
ring  of  cartilage  on  the  upper  nasal  rim  of  the  socket  and 
then  turns  backward  to  be  attached  behind  the  centre  of 
the  upper  surface  of  the  eyeball.  The  inferior  obHque 
springs  from  the  lower  nasal  rim  of  the  socket  and  passes 
back  to  a  point  behind  the  middle  of  the  lower  surface. 
From  the  fact  that  the  oblique  muscles  exert  their  pull  to- 
ward the  front,  they  turn  the  eyes  in  the  direction  opposed 
to  their  names.  The  direction  in  which  the  muscles  turn 
the  eyeball  may  be  best  indicated  by  the  diagram  taken 
from  Hering.  It  will  be  seen  that  the  internal  and  exter- 
nal recti  muscles  turn  the  eye  in  an  approximately  straight 
line;  all  the  others  turn  it  along  a  curv^  and  if  the  eye  is 
to  be  moved  directly  up  or  directly  down,  two  muscles 
must  cooperate  (Fig.  73). 

Eye-movements.  —  The  eyeball  turns  about  a  point 
about  1.3  mm.  behind  the  centre  of  the  eye.  The  centre  of 
rotation  is  13.5  mm.  back  of  the  cornea.  It  should  not  be 
assumed  that  this  point  is  absolutely  fixed,  —  owing  to  the 
loose  way  in  which  the  eyeball  is  held  in  its  socket,  it  is 
slightly  displaced  as  it  turns,  and  the  centre  of  rotation 
moves  with  it.  Also  as  the  eyeball  turns,  it  is  rotated 
more  or  less  about  its  optic  axis.  This  is  called  torsion. 
The  amount  of  torsion  increases  with  the  amount  of  the 
movement,  but  is  always  present  even  for  sKght  move- 
ments. Both  eyes  always  move  together.  A  single  im- 
pulse is  seht  simultaneously  to  the  same  muscles  of  both 
eyes.    It  is' as  if  they  were  a  team  of  horses  turned  by  a 


3o8        FUNDAMENTALS   OF  PSYCHOLOGY 

single  pull  on  a  pair  of  reins.  These  movements  follow  the 
direction  of  attention,  as  was  said  in  an  earlier  chapter. 
The  only  conscious  antecedent  is  that  some  object  in  the 
field  of  vision  shall  catch  the  attention,  then  the  eye  mus- 
cles immediately  contract  in  a  way  to  bring  both  eyes  to 
fixate  the  object.     As  points  of  reference  for  eye  move- 


•.t^i. 


ao  so        10 


10  20  30  40 


Fig.  73.  —  Hering's  diagram  of  eye-movements,  showing  zonht  the  eye  would  fol- 
low if  pulled  by  each  muscle  singly. 

ments,  one  may  distinguish  certain  positions.  What  is 
known  as  the  primary  position  is  that  which  the  eyes  have 
when  fixed  on  a  distant  object  in  the  median  plane  and  a 
little  (15°)  below  the  horizontal.  From  this,  movements 
may  be  made  in  any  direction  with  the  optic  axes  parallel, 
or  the  eyes  may  be  converged  upon  points  in  the  median 
plane  or  to  one  side  of  it.    These  positions  have  been  called 


PERCEPTION  OF  VISUAL  SPACE  309 

secondary  and  tertiary,  but  no  agreement  as  to  which  are 
to  be  called  secondary  and  which  tertiary  has  been  attained. 
The  Two  Eyes  are  One  for  Vision.  —  The  fact  that  we 
always  use  two  eyes  instead  of  one  offers  interesting  prob- 
lems as  to  how  two  impressions  can  combine  in  one,  what 
part  each  contributes,  and  the  advantages  of  binocular  as 
compared  with  monocular  vision.  In  general,  it  may  be 
said  that  for  most  purposes  the  two  eyes  act  almost  as  one 
organ.  If  a  plane  surface  be  presented  to  both  eyes,  we 
see  it  single  and  not  appreciably  different  from  the  same 
surface  as  seen  by  a  single  retina. 
When  different  objects  are  presented 
to  the  surfaces  of  the  two  retinas, 
the  result  may  be  that  (i)  the  two 
may  fuse  to  produce  a  new  quality, 

I'iG.  74. —  Stereoscope  slide 

(2)  one  may  suppress  the  other  en-  that  shows  the  effect  of  con- 
tirely,  or  (3)  first  one  may  be  seen,  ^^h  J^Zp  JhlC") 
then  the  other.     Colors  which  fuse 

when  they  fall  upon  the  same  surface  in  a  single  eye  are  likely 
to  fuse  when  one  stimulates  one  retina,  the  other  the  other. 
For  certain  individuals  there  may  be  an  alternation.  Thus, 
if  one  half  of  a  stereoscopic  sHde  be  red  and  the  other  blue, 
when  looked  at  in  the  stereoscope  they  will  ordinarily  give 
a  purple,  but  at  times  and  in  part  of  the  field  an  individual 
will  see  first  the  red  and  then  the  blue.  Where  a  contour 
of  any  kind  is  presented  to  one  eye  and  a  uniform  surface  to 
the  other,  as  in  Figure  74,  the  contours  will  be  noticed  and 
the  plain  surface  neglected.  The  law  may  be  formulated 
in  the  statement  that  you  see  what  means  most  to  you, 
what  is  most  interesting,  while  you  neglect  the  unimpor- 
tant plain  surface.  Where  two  colors  or  grays,  alike  except 
in  brightness,  are  combined,  the  result  is  a  single  color  with 
a  brightness  intermediate  between  that  of  the  components. 


3IO        FUNDAMENTALS   OF  PSYCHOLOGY 

The  brightness  is  usually  a  little  greater  than  the  average 
for  the  two  stimuU.  Thus,  when  the  two  are  of  the  same 
brightness,  the  brightness  of  the  combined  image  may  be 
ro  greater  than  that  of  either  alone,  and  when  they  are 
very  different,  the  brighter  may  have  its  brightness  reduced 
by  the  darker.  This  latter  is  known  as  Fechner's  paradox, 
since  the  addition  of  the  fainter  brightness  to  the  greater 
reduces  rather  than  increases  the  brighter.  A  contrast  color 
may  also  be  induced  in  one  eye  by  stimulation  of  the  other. 
Corresponding  Points.  —  Very  important  for  the  space 
problems  is  an  understanding  of  the  arrangement  of  the 
points  or  lines  that  are  seen  singly.  If  vertical  lines,  one 
on  one  half,  the  other  on  the  other  half  of  the  stereoscope 
slide,  be  seen  in  the  stereoscope,  it  will  be  found  that  the 
lines  will  be  seen  as  one  if  they  are  so  placed  that  the  im- 
ages fall  on  identical  points,  i.e.,  on  points  that  are  the 
same  distance  from  the  fovea  and  in  the  same  direction. 
If  both  are  vertical  and  pass  through  the  centre  of  the 
fovea,  they  will  be  seen  as  one;  if  one  pass  through  the 
fovea,  the  other  through  a  point  one  degree  to  either  side 
of  it,  both  will  be  seen.  Identical  points  may  be  defined  as 
those  equidistant  from  the  fovea  and  in  the  same  direction 
from  it.  If  the  two  retinas  could  be  placed  one  over  the 
other  in  such  a  way  that  the  foveas  and  the  vertical  and 
horizontal  axes  coincided,  then  all  points  that  were  super- 
imposed would  be  identical  points.  Stated  in  terms  of 
rays  of  light,  those  rays  fall  upon  identical  points  which 
make  the  same  angle  with  the  lines  of  sight  of  each  eye 
and  in  the  same  direction.  The  line  of  sight  is  the  line 
from  the  fixation  point  to  the  centre  of  the  fovea.  Corre- 
sponding points  are  those  points  which  in  practice  com- 
bine to  give  a  single  image.  Identical  points  are  defined 
geometrically.   Ordinarily  they  agree  for  practical  purposes. 


PERCEPTION  OF  VISUAL  SPACE  311 

A  most  important  problem  for  the  perception  of  space  is 
to  determine  how  much  two  stimuh  may  depart  from  cor- 
respondence before  they  can  be  seen  as  two;  or,  in  terms 
of  our  first  problem,  how  far  the  two  Unes  on  the  stereo- 
scopic sUde  may  depart  from  correspondence  before  they 
will  seem  to  be  two.  Pulfrich^  and  Bourdon^  found  that 
two  objects  need  have  no  greater  deviation  from  corre- 
spondence than  from  5"  to  12"  for  the  deviation  to  be 
noticed.  This  is  considerably  less  than  the  'limen  of  two- 
ness'  for  a  single  eye.  It  should  be  added  that  the  lines 
are  not  necessarily  seen  as  two,  but  the  divergence  may  be 
translated  into  depth,  as  will  be  seen  in  a  later  discussion. 
Considerably  greater  deviations  from  correspondence  may 
take  place  without  being  noticed  if  the  Hues  are  horizontal 
than  if  vertical. 

Why  two  points  should  thus  give  rise  to  but  a  single 
image  is  not  easy  to  say.  The  first  theory,  suggested  by 
Johannes  Mliller,  was  that  it  was  due  to  the  fact  that  cor- 
responding points  were  connected  with  the  same  half  of  the 
brain.  It  is  a  fact  that  the  right  half  of  each  retina  is  con- 
nected with  the  right  hemisphere,  and  each  left  half  with 
the  left  hemisphere.  There  is,  as  the  diagram  (p.  54) 
shows,  only  a  partial  crossing  at  the  chiasma,  —  half  of 
the  fibres  cross  and  half  go  uncrossed  to  the  same  side  of 
the  brain.  Mliller  assumed  that  these  fibres  in  some  way 
combine  in  the  cortex,  perhaps  connect  with  the  same 
cells,  and  so  give  rise  to  a  single  image.  This  would  be 
the  nativistic  explanation;  the  combination  would  be  due 
to  the  innate  nervous  connections.  The  empiricist,  how- 
ever, can  cite  numerous  cases  in  which  this  correspondence 
is  changed  by  experience.     Individuals  whose  eyes  are 

1  Physikalische  Zeitschrift,  1899,  No.  9. 

2  Revue  Philosophique,  Vol.  25,  p.  74. 


312        FUNDAMENTALS   OF  PSYCHOLOGY 

badly  crossed,  who  squint,  develop  a  new  set  of  corre- 
sponding points;  the  points  that  have  been  used  in  seeing 
the  same  object  come  to  give  single  images,  or  else  the 
image  from  one  eye  is  disregarded.  Similarly,  horizontal 
Hnes  may  be  a  considerably  greater  distance  apart  than 
vertical  ones  and  still  correspond.  Under  those  circum- 
stances experience  makes  it  more  likely  that  there  is  one 
line  than  two.  If  the  lines  be  vertical  and  deviate  very 
slightly  from  correspondence,  they  will  be  seen  as  two. 
We  shall  see  that  this  deviation  from  correspondence  of 
vertical  lines  is  an  important  factor  in  the  appreciation  of 
distance,  and  is  therefore  noticed;  while  the  necessity  for 
distinguishing  horizontal  lines  is  relatively  slight.  The 
empiricist's  explanation  would  be  that  we  see  the  two  im- 
ages as  one,  because  tests  by  touch  or  other  senses  have 
shown  that  there  is  only  one  object  present  in  spite  of  the 
two  images;  we  have  learned  that  two  images  mean  one 
object,  and  the  positions  that  are  most  frequently  stimulated 
together  by  a  single  object  become  corresponding  points. 

The  Horopter.  —  The  problems  of  binocular  vision  and 
corresponding  points  are  of  interest  because  of  the  light 
that  they  throw  upon  the  positions  that  objects  in  space 
must  occupy  if  they  are  to  be  seen  singly.  When  the  eyes 
are  converged  in  a  given  position,  there  is  only  one  dis- 
tance from  which  rays  of  Hght  can  fall  upoii  corresponding 
points.  The  distance  varies  as  convergence  varies,  but  the 
locus  of  points  in  space  which  will  send  rays  to  correspond- 
ing points  is  strictly  limited.  Points  nearer  or  more  re- 
mote will  fall  upon  non-corresponding  points  and  so  give 
double  images.  The  locus  of  all  points  that  fall  upon 
corresponding  points  is  called  the  horopter.  The  form 
of  the  horopter  has  been  developed  mathematically  in 
great  detail.     Since  the  assumptions  upon  which  the  com- 


PERCEPTION  OF  VISUAL   SPACE 


313 


putations  are  based  do  not  correspond  accurately  to  the 
actual  facts  of  vision,  we  need  pay  little  attention  to  the 
intricacies  of  the  calculations.     Two  forms  of  the  horopter 


F    b 


a'  F 


Fig.  75.  —  Miiller's  Horopter  Circle,  a  and  a',  b  and  b'  are  corresponding  points. 
Lines  drawn  from  these  points  through  the  nodal  point  will  meet  in  a  circle  that 
passes  through  the  fixation  point  F  and  through  the  two  nodal  points,  n  and  n'. 


may  be  mentioned.  When  the  eyes  are  converged  upon 
a  point  in  the  plane  halfway  between  them,  the  horopter 
is  a  circle  passing  through  the  fixation  point  and  the  nodal 
points  of  both  eyes.     To  this  is  added  a  vertical  line 


314        FUNDAMENTALS   OF  PSYCHOLOGY 

through  the  fixation  point.  When  the  eyes  are  parallel,  all 
points  at  an  infinite  distance,  the  distance  at  which  paral- 
lel hnes  meet,  would  fall  in  the  horopter,  theoretically.  In 
practice,  the  horopter  is  composed  of  all  space  beyond  the 
point  where  the  departure  from  the  parallel  is  less  than  5", 
the  least  disparateness  that  can  be  appreciated,  or  beyond 
a  distance  of  some  2500  metres. 

The  Perception  of  Distance.  —  We  have  now  to  consider 
the  application  of  the  different  facts  of  vision  so  far  col- 
lected to  the  perception  of  the  distance  of  objects  from  us 
—  which  may  be  called  depth  or  the  third  dimension.  We 
may  speak  first  of  the  elements  which  are  derived  from  the 
structure  of  the  eyes  and  which  in  consequence  are  usually 
termed  the  primary  or  physiological  factors.  With  the 
single  eye  the  most  important  is  the  accommodation  of  the 
lens  for  different  distances.  As  was  said  in  Chapter  IV. 
when  a  near  object  is  attended  to,  the  ciHary  muscle  is  con- 
tracted and  this  permits  the  lens  to  thicken  and  give  a  clear 
image  of  the  object.  On  the  other  hand,  when  a  more  dis- 
tant object  is  attended  to,  the  cihary  muscle  is  relaxed  and 
the  lens  is  flattened  by  the  tension  on  the  suspensory  hga- 
ment  and  so  adapted  to  receive  a  clear  image  from  distant 
objects.  The  degree  of  strain  varies  inversely  as  the  dis- 
tance, and  is  immediately  interpreted  to  mean  the  distance 
of  the  object.  One  thinks  of  objects  that  are  seen  with 
much  strain,  as  near;  those  that  are  seen  without  strain,  as 
remote.  (No  strain  is  required  for  objects  more  than  about 
50  feet  away.)  As  is  usual  in  all  perception,  these  factors 
are  not  observed  in  themselves;  the  distance  alone  ordi- 
narily comes  to  consciousness. 

Convergence  as  a  Factor  in  Distance  Perception.  —  When 
two  eyes  are  used  for  the  appreciation  of  distance,  estimates 
are  much  more  accurate  than  when  one  eye  is  used.    If  a 


PERCEPTION  OF  DEPTH 


315 


man  looks  with  one  eye  at  a  landscape,  he  notices  that  it 
appears  much  flatter  than  usual.  Or  if  one  attempts  to 
put  a  finger  through  a  ring  held  sidewise  by  another,  it  will 
be  found  very  difficult  when  one  eye  is  closed,  although 
perfectly  easy  when  both  eyes  are  open.  New  factors 
obviously  must  be  added  when  both  eyes  are  used.  Two 
of  these  are  important.  One  is  muscular,  the  movements 
required  to  converge  the  eyes  upon  a  single  object.  Distant 
objects  are  xdewed  with  the  eyes  nearly  parallel  and  with 
the  muscles  fairly  completely  relaxed.    As  an  object  comes 

TABLE   II 


nearer,  it  is  necessary  to  contract  the  internal  recti  muscles 
that  the  eyes  may  be  converged  to  see  it  with  the  foveas. 
This  gives  rise  to  another  strain  that  also  decreases  with 
the  distance.  This  strain  is  a  more  accurate  index  of  dis- 
tance and  can  furthermore  be  used  to  detect  distance  over 
a  longer  range  than  the  strain  of  accommodation.  If  one 
compare  the  distance  of  a  thread  seen  at  different  distances 
first  with  one  eye  then  wdth  both,  under  conditions  that  re- 
strict the  means  of  determining  distance  to  the  muscular 
adjustment,  it  is  found  that  the  distances  that  can  be 
distinguished  are  much  less  in  the  latter  case  than  in  the 


3i6        FUNDAMENTALS   OF  PSYCHOLOGY 

former.  This  is  shown  in  the  table  on  page  315  taken 
from  Wundt. 

The  distance  is  the  absolute  distance  from  the  eye;  the 
limen,  the  difference  in  distance  that  can  be  just  noticed; 
while  the  relative  limen  is  the  limen  for  binocular  vision 
divided  by  the  absolute  distance.  This,  it  will  be  noticed, 
is  approximately  the  same  as  the  difference  limen  for  the 
comparison  of  horizontal  lines  on  a  flat  surface,  in  which 
movements  have  also  been  regarded  as  an  important  factor. 

Double  Images  in  the  Perception  of  Distance.  —  Still 
another  indication  of  the  distance  of  objects  is  given  by 
the  differences  in  the  images  of  the  objects  on  the  two 
retinas.  One  may  be  said  to  get  a  different  image  of  a  dis- 
tance with  each  eye.  If  one  hold  a  ruler  end  on  in  front 
of  the  eyes  and  close  first  one  eye  and  then  the  other,  it 
will  be  noted  that  the  image  shifts  as  the  eyes  are  changed. 
If  one  converges  upon  the  far  end,  with  both  eyes  open,  the 
near  end  will  be  seen  double,  while  if  one  looks  at  the  nearer 
end,  the  farther  will  be  double.  In  either  case  the  image  of 
the  ruler  will  slant  from  the  double  to  the  single  end.  These 
double  images  will  not  be  noticed  at  first  but  will  be  used 
as  immediate  signs  of  the  distance  of  one  end  from  the  other. 
Similarly,  if  two  threads  are  present  simultaneously  in 
the  field  of  vision  at  different  distances,  the  one  fixated  will 
be  seen  single,  the  other  double,  and  will  be  separated  by  a 
space  that  increases  with  the  distance  between  the  threads. 
This  doubleness  is  of  value  only  in  determining  the  distance 
between  two  objects  or  points,  not  for  the  determination 
of  the  absolute  distance  of  a  single  object.  The  degree  of 
doubleness  changes  with  each  position  of  the  eyes  as  well 
as  with  the  distance  of  the  object.  Given  the  absolute 
distance  of  any  point  of  reference,  the  distance  of  any  other 
point  from  that  in  the  field  of  vision  may  be  determined. 


PERCEPTION   OF  DEPTH 


317 


Not  only  may  the  distance  between  two  points  be  estimated 
in  this  way  but  also  which  is  nearer  the  observer.     If  one 


Fig.  76.  —  To  illustrate  crossed  and  uncrossed  images.  F  is  the  tixation  point 
and  is  seen  singly.  An  image  of  a  more  distant  point  .1  falls  upon  points  a  and  a' 
on  the  retinas,  which  are  non-corresponding.  As  excitations  of  the  retina  are  pro- 
jected to  the  plane  of  the  fixation  point,  they  are  seen  at  A'  and  A  "  and  are  there- 
fore uncrossed,  the  image  seen  with  the  right  eye  is  seen  to  the  right  of  the  fixation 
point  and  to  the  right  of  the  image  seen  with  the  left  eye.  Objects  nearer  than  the 
fixation  point,  as  B,  will  also  be  projected  to  the  fixation  plane  at  B'  and  B '  and  so 
are  crossed,  the  image  on  the  right  retina  is  seen  as  if  it  were  to  the  left  of  the  fixa- 
tion point  antl  vice  versa. 

fixate  the  more  remote,  the  double  images  are  crossed;  that 
is,  the  one  on  the  right  is  seen  with  the  left  eye,  and  vice 
versa.    If  one  fixate  the  nearer,  the  more  remote  gives  un- 


3i8 


FUNDAMENTALS   OF  PSYCHOLOGY 


crossed  double  images.  This  can  be  tested  by  closing  one 
eye.  It  will  be  noticed  that  when  the  farther  object  is 
looked  at  and  one  eye  is  closed,  the  image  on  the  opposite 


Fig.  77.  —  Diagram  of  prism  stereoscope.     (From  Titchener,  " E.xperimental  Psy- 
chology.") 


side  disappears;  when  the  nearer  object  is  fixated,  the 
image  on  the  same  side  disappears.  This  occurs  because 
the  double  images  are  always  referred  to  the  plane  of  the 
fixation  point  in  considering  their  relative  position  as  on 
the  right  or  on  the  left.  This  can  be  seen  by  study  of  the 
diagram  (Fig.  76). 


PERCEPTION  OF   DEPTH 


319 


These  double  images  constitute  one  of  the  important 
features  in  estimating  depth  in  our  ordinary  perceptions. 
As  one  looks  at  any  landscape  with  the  eyes  converged  upon 
some  object  in  the  middle 
distance,  all  nearer  objects 
are  seen  double  in  crossed 
images;  all  more  remote 
objects  are  seen  double  in 
uncrossed  images,  and  the 
degree  of  doubleness  in- 
creases with  the  distance 
from  the  object  fixated. 
These  double  images  are 
not  ordinarily  seen  for  them- 
selves, but  are  at  once  trans- 
lated into  distance,  just  as 
are  the  strains  of  accom- 
modation and  convergence. 
However,  they  can  be 
noticed  with  a  httle  prac- 
tice. So  close  has  become 
the  association  between 
double  images  and  the  per- 
ception of  distance  that 
when  letters  are  printed  to  appear  double,  they  seem 
nearer  or  farther  even  when  viewed  with  a  single  eye. 
The  importance  of  the  double  images  may  be  shown 
by  the  use  of  the  ordinary  stereoscope  which  depends  for 
its  effect  upon  the  fact  that  the  two  pictures  represent 
the  image  that  would  be  seen,  one  by  the  left,  the  other  by 
the  right  eye,  were  one  standing  at  the  point  occupied  by 
the  double  camera  when  the  picture  was  taken.  The 
prisms  in  the  stereoscope  turn  the  rays  of  light  sufficiently 


Fig.  78.  —  Diagram  of  prism   pseudo- 
scope.     (From  Titchener,  op.  cit.) 


320        FUNDAMENTALS   OF  PSYCHOLOGY 

to  have  them  enter  the  eyes  as  if  they  came  from  a  single 
object  rather  than  from  two.  The  difference  in  the  two 
pictures  gives  the  same  degree  of  doubleness  that  would  be 
given  by  the  single  object,  and  is  interpreted  as  distance 
just  as  it  is  in  actual  space  perception.  Increasing  the 
distance  between  the  cameras  that  take  the  pictures,  in- 
creases the  apparent  depth. 

Pseudoscope  and  Teleostereoscope.  —  Even  more  strik- 
ing is  the  effect  of  the  pseudoscope.  If  the  relations  of  the 
double  images  are  reversed,  as  may  be  done  in  the  stereo- 
scope by  interchanging  the  picture  belonging  to  the  right 
eye  and  that  belonging  to  the  left,  the  nearer  objects  appear 
farther  away,  the  more  distant  nearer  than  the  point  of 
fixation.  The  same  effect  may  be  obtained  with  real  objects 
by  using  the  pseudoscope  devised  by  Wheatstone.  This 
consists  of  two  right-angle  prisms  mounted  in  tubes  that 
can  be  brought  one  before  each  eye.  The  images  are 
reversed  in  passing  through  the  prisms,  and  this  makes 
the  images  that  come  from  the  nearer  object  enter  the  eyes 
as  if  they  came  from  the  more  remote;  the  character  of 
the  double  images  is  reversed,  those  from  objects  more 
remote  than  the  fixation  point  are  crossed,  those  from 
objects  nearer  than  the  fixation  point  are  uncrossed.  In 
consequence,  the  distance  interpretations  are  also  reversed. 
The  inside  of  a  mask  when  viewed  through  the  stereoscope 
will  appear  to  be  the  outside,  the  nearer  of  two  threads  will 
seem  to  be  more  remote,  etc.  It  is  to  be  noted  that  the  ef- 
fect is  much  easier  to  obtain  if  the  inside  of  the  mask  be 
painted  to  correspond  with  the  design  of  the  outside,  and 
is  so  hghted  as  to  avoid  strong  shadows.  Another  indication 
of  the  importance  of  double  images  in  the  perception  of 
distance  is  furnished  by  the  teleostereoscope.  This  instru- 
ment consists  in  principle  of  two  pairs  of  mirrors,  P,  P,  one 


PERCEPTION  OF  DEPTH  321 

before  each  eye,  and  another,  M,  M,  at  a  httle  distance  to 
the  outside  to  receive  the  rays  of  light  from  the  object.  The 
effect  is  to  increase  the  degree  of  doubleness,  and  to  make 
the  perception  of  distance  as  accurate  as  it  would  be  if  the 
eyes  were  as  far  apart  as  the  more  widely  separated  mirrors 
that  first  receive  the  rays  of  light.  The  course  of  the  rays 
may  be  made  out  from  Fig.  79.  A  similar  device  is  used 
in  the  better  field  glasses  at  present.  Surfaces  of  prisms 
supply  the  mirrors  and  these  are  separated  by  a  much 
smaller  distance  to  make  the  instrument  more  portable, 

\ 
/ 

M    /  \     M. 


-^ br      ^ <- 

i  R 

Fig.  7g.  — Teleostereoscope.    (From  Titchener,  op.  cit.) 

but  they  serve  to  increase  markedly  the  accuracy  of  the 
estimation  of  distance. 

These  three  factors,  the  strain  of  accommodating  the  eye 
to  different  distances,  the  strain  of  converging  the  eyes  upon 
an  object,  and  the  double  images,  constitute  the  signs  of 
depth  that  may  be  said  to  depend  upon  the  structure  of  the 
organs,  and  are  sometimes  called  the  primary  factors.  They 
vary  in  accuracy,  —  accommodation  is  least  accurate,  con- 
vergence about  five  times  as  accurate,  and  double  images 
much  more  accurate  than  either  of  the  others.  They  also 
vary  in  the  distance  at  which  they  are  effective.  Accommo- 
dation is  an  aid  only  for  objects  nearer  than  fifty  feet;  con- 
vergence is  effective  up  to  about  300  feet.    Under  the  best 


322        FUNDAMENTALS   OF  PSYCHOLOGY 

conditions  double  images  give  an  idea  of  distance  up  to 
about  2500  yards.  Beyond  that,  the  more  distant  objects 
show  no  appreciable  doubleness  of  images,  although  of 
course  all  nearer  objects  are  seen  as  double.  In  each  case 
the  distance  alone  is  really  seen;  the  strains  or  double 
images  that  have  been  mentioned  are  not  noticed.  The 
distance  directly  inferred  is  not  any  single  mental  image  or 
sensation,  any  more  than  is  the  local  sign,  but  is  appre- 
ciated as  distance. 

The  Psychological  Factors.  —  While  these  primary 
factors  make  estimation  most  accurate,  many  other  signs 
of  distance  are  of  great  value.  The  others  consist  of 
changes  in  the  character  of  the  image  as  the  distance 
changes.  They  are  the  secondary  or  psychological  factors. 
Perhaps  the  most  important  of  these  is  perspective.  The 
size  of  an  object  is  inversely  proportional  to  the  distance. 
If  one  knows  the  size  of  any  object  in  the  field  of  vision, 
it  is  altogether  possible  to  infer  its  distance  from  its  ap- 
parent size,  the  size  of  the  image.  The  importance  of 
this  means  of  obtaining  an  idea  of  distance  may  be  gathered 
from  the  use  of  perspective  in  art.  The  distance  ascribed 
to  an  object  in  a  photograph  or  painting  depends  very 
largely  upon  its  size,  relative  to  other  objects  in  the  photo- 
graph. Here,  as  in  the  other  factors,  the  estimates  of 
distance  are  not  made  consciously;  one*  does  not  first 
notice  the  diminished  size  and  then  infer  how  far  away  the 
object  must  be  to  give  that  distance,  but  sees  the  distance 
at  once,  and  corrects  the  size  of  the  object  in  accordance 
with  his  estimate  of  its  distance.  The  object  seems  to  be 
of  full  size  and  at  the  correct  distance.  The  tendency  to 
overlook  the  difference  in  size  is  evident  from  the  relatively 
late  development  of  perspective  in  art.  The  early  paintings 
and  bas-rehefs  make  distant  objects  of  the  same  size  as  the 


PERCEPTION  OF   DEPTH  323 

nearer  ones.  Obviously  the  early  artist  had  not  noticed 
the  phenomenon  of  perspective  but  inferred  distance  with- 
out knowing  how.  Even  now  an  artist  often  draws  his 
distant  objects  larger  than  they  should  be. 

A  second  factor  under  this  head  is  the  higher  position  of 
more  distant  objects  in  the  field  of  view.  Objects  on  a  flat 
ground  plane  appear  to  rise  gradually  as  they  go  away  from 
the  eyes  and,  with  proper  allowance  for  the  actual  height 
of  the  object  above  the  ground  plane,  the  relative  height 
may  be  used  as  a  measure  of  distance.  This  factor  was 
recognized  by  the  early  artists.  Their  distant  figures  are 
placed  higher  than  the  nearer,  an  arrangement  that  makes 
it  possible  to  show  the  more  remote,  as  well  as  to  imitate  the 
apparent  effects  of  distance.  The  haziness  or  distinctness 
of  objects  is  also  an  important  factor.  This  can  be  seen 
from  the  tendency  to  mistake  distant  objects  for  near, 
where  the  air  is  particularly  clear.  In  theatres  it  is  cus- 
tomary to  draw  a  net  in  front  of  the  more  remote  parts  of 
the  scene.  Distant  objects  appear  blue.  Both  of  these 
effects  are  due  to  the  absorption  of  light  waves  by  the  air 
intervening  between  the  object  and  the  observer.  The 
condition  is  sometimes  called  air  perspective.  An  element 
almost  too  obvious  to  mention,  but  nevertheless  highly 
important  in  practice,  is  superposition.  The  partly 
hidden  object  must  be  more  remote  than  the  one  fully 
seen. 

Motion  an  Aid  to  Distance  Perception.  —  Motion,  both 
of  the  observer  and  of  the  object,  aids  in  the  perception  of 
depth.  When  the  head  is  moved  to  one  side,  all  objects 
in  the  field  of  vision  are  displaced  in  different  degrees.  If 
one  is  looking  at  any  object  in  the  middle  distance,  all 
nearer  objects  shift  in  the  direction  opposite  to  the  move- 
ment, all  more  remote  ones  in  the  same  direction  as  the 


324        FUNDAMENTALS   OF  PSYCHOLOGY 

movement.  The  amount  of  the  apparent  displacement 
increases  with  the  distance  between  the  object  and  the 
fixation  point.  When  one  is  in  rapid  motion  as  in  a  railway 
carriage  or  an  automobile  and  is  looking  at  a  point  in  the 
middle  distance,  there  is  a  constant  procession  of  the  near 
objects  backward  and  the  more  remote  objects  forward, 
at  a  rate  that  depends  upon  their  distance  and  the  rate  of 
motion.  This  gives  a  notion  of  distance.  When  objects 
are  themselves  in  motion,  the  apparent  rate  of  motion  com- 
pared with  the  usual  rate  of  the  object  at  a  standard 
distance  serves  as  an  indication  of  its  distance.  When  seen 
from  a  rapidly  moving  vehicle  objects  seem  smaller  than 
usual  because  they  seem  to  be  moving  much  more  rapidly 
than  usual.  This  means  that  they  are  regarded  as  much 
nearer  than  they  really  are,  and  this  by  the  habits  of  per- 
spective makes  them  seem  small. 

Shadows  in  Space  Perception.  —  Another  factor  that  aids 
in  determining  the  form  of  objects  in  the  third  dimension 
is  the  interpretation  put  upon  shadows  and  high  Hghts. 
The  nearer  surfaces  are  usually  well  illuminated  while  the 
more  remote  are  more  or  less  in  the  shadow.  This  is  trans- 
lated at  once  into  depth  or  distance  and  the  shadows  them- 
selves are  Kttle  noticed.  Shadows  are  much  used  by  the 
artist;  in  fact  they  are  quite  as  important  as  perspective 
in  enabHng  him  to  represent  depth  in  the  contour  of  an  ob- 
ject on  the  flat  canvas.  In  the  real  object,  much  depends 
upon  the  knowledge  of  the  direction  from  which  the  light 
comes,  or  from  assumptions  that  are  made  concerning  the 
direction.  If  one  will  look  at  a  cameo  under  a  microscope 
which  reverses  the  image,  it  seems  to  become  an  intagho. 
The  high  hghts  fall  on  the  side  that  they  would  were  the 
depth  relations  reversed,  and  the  depth  is  also  reversed.  In 
depressions  made  in  steel  by  a  smooth  ball  Hghted  from  all 


PERCEPTION  OF  AUDITORY   SPACE       325 

sides  to  give  numerous  reflections,  it  is  quite  easy  to  see 
the  depression  as  a  protuberance. 

Depth  for  vision,  then,  is  appreciated  by  virtue  of  a 
number  of  differences  in  the  sensations  that  come  from  the 
muscles  of  the  eye,  external  and  internal;  in  the  difference 
in  an  object  as  it  is  seen  by  the  right  eye  and  by  the  left; 
and  by  a  number  of  peculiarities  of  the  image  of  an  object 
that  change  with  the  distance.  These  sensations  are  not 
first  seen  for  themselves  and  then  associated  with  the  idea 
of  distance,  but  as  a  result  of  their  presence  the  object  is 
at  once  seen  at  the  corresponding  distance.  In  this  respect 
the  third  dimension  is,  Hke  the  other  two  dimensions  and 
the  idea  of  position,  apparently  received  immediately,  and 
can  be  analyzed  into  its  elements  only  indirectly. 

Auditory  Space 

Auditory  Perception  of  Space.  —  One  other  sort  of  per- 
ception of  distance  needs  to  be  mentioned,  the  perception 
of  the  position  and  distance  of  sounds.  Unlike  tactual  and 
visual  sensations,  there  is  in  sound  no  really  two-dimen- 
sional space,  no  perception  of  objects  in  contact  with  the 
sense  organ,  but  merely  perception  of  the  distance  and  direc- 
tion of  objects  that  give  rise  to  sounds.  These  locahzations 
are  relatively  uncertain  and  indefinite.  One  is  constantly 
deceived  as  to  the  distance  and  direction  of  sounds.  The 
breathing  of  a  dog  on  the  hearth  may  be  mistaken  for  dis- 
tant thunder  or  some  other  intense  but  distant  noise.  Front 
and  back  are  often  confused.  Right  and  left  much  less 
often;  but  still  under  the  influence  of  suggestion,  confusions 
of  this  sort  are  far  from  infrequent.  Experiments  indicate 
that  the  primary  factor  in  the  perception  of  distance  is  the 
intensity  of  the  sound  as  compared  with  the  sound  given 
at  some  known  or  standard  distance.     This  implies,  first, 


326        FUNDAMENTALS   OF  PSYCHOLOGY 

a  recognition  of  the  source  of  the  sound,  then  an  association 
between  the  present  intensity  of  the  sound  and  the  distance 
that  would  give  the  particular  intensity.  A  locomotive 
whistle  has  been  heard  at  a  large  number  of  distances,  more 
or  less  accurately  observed  or  measured.  When  it  is  recog- 
nized, its  intensity  at  once  suggests  the  distance.  This  is 
true  of  any  famihar  sound.  If  the  sound  be  altogether 
unfamiliar,  appreciation  of  distance  is  difficult,  although 
if  it  be  recognized  as  belonging  to  some  known  class,  an 
estimate  can  usually  be  made. 

The  Appreciation  of  the  Direction  of  Sounds.  —  Percep- 
tion of  direction  depends  upon  three  factors,  —  the  relative 
intensity  of  the  sound  heard  with  each  ear,  the  timbre  of 
the  sound,  and  its  intensity.  A  sound  on  the  left  will 
excite  the  left  ear  more  than  the  right.  A  more  ac- 
curate notion  of  the  direction  of  the  sound  may  be 
gathered  from  the  relative  strength  of  the  effects  upon 
the  two  ears. 

Recently  evidence  has  been  accumulating  in  favor  of 
Lord  Rayleigh's  suggestion  that  perception  of  direction 
depends  upon  the  difference  in  phase  of  the  tones  as  they 
reach  the  ears.  As  the  tones  from  directions  other  than 
directly  in  front  or  directly  behind  must  travel  different 
distances  to  reach  the  two  ears,  they  would  be  in  different 
phases.  For  example,  if  the  difference  in  distance  were 
half  a  double  vibration,  in  length,  the  tone  on  the  nearer 
ear  would  be  pulUng  the  drum  out  while  that  on  the  farther 
ear  were  pushing  the  drum  in.  Usually  the  difference  in 
phase  would  not  be  so  great,  but  always  appreciable. 
Stewart  ^  has  demonstrated  that  when  tones  fall  upon  the 
two  ears  in  different  phases,  the  apparent  position  changes, 
although  the  real  position  remains  constant.     This  is  prob- 

^  Stewart,  Physical  Review,  vol.  9,  191 7,  pp.  502-528. 


PERCEPTION  OF  AUDITORY  SPACE 


327 


ably  even  more  important  than  the  relative  intensity  in 
determining  the  direction  of  the  sounding  body. 

Distinguishing  between  sounds  which  come  from  in  front 
and  behind  offers  greater  difhculties.  With  pure  tones  it  is 
almost  impossible.  If  two  tuning  forks  of  the  same  pitch 
be  vibrating,  one  directly  in  front,  the  other  directly  behind, 
and  one  be  stopped,  it  is  almost  impossible  to  tell  which  is 
still  sounding.  The  percentage  of  mistakes  will  approach 
fifty.  If  the  sounds  be  complex,  are  noises,  or  from  instru- 
ments rich  in  overtones,  fewer  mistakes  are  made.  This 
suggests  that  the  quaHty  of  the  tone  is  in  some  way  modi- 
fied by  the  direction  from  which  the  tone  comes.  Angell 
asserts  that  this  may  be  due  to  the  way  in  which  the  various 
overtones  are  modified  when  the  tone  strikes  the  outer  ear. 
From  one  direction,  one  overtone  or  group  of  overtones  will 
be  reenforced,  from  another  direction  another  will  be 
strengthened,  and  the  resulting  complex  tones  enable  one 
to  determine  the  direction.  Myers*  has  shown  experimen- 
tally that  changes  in  the  timbre  of  a  tone  will  induce  changes 
in  localization.  If  a  tone  be  sounded  directly  in  front  until 
the  observer  has  acquired  practice  in  localizing,  and  then 
the  component  parts  of  the  tone  be  changed  to  give  it  a 
different  quaHty,  the  sound,  although  still  coming  from  in 
front,  will  be  localized  in  some  other  position.  Myers 
found,  too,  that  when  he  placed  short  rubber  tubes  in  the 
ears,  all  capacity  for  determining  the  position  of  sounds 
disappeared.  These  tubes  made  it  impossible  for  the 
external  ear  to  modify  the  quality  of  the  tones  or  their 
intensity.  Changes  in  the  intensity  of  the  sound  also  induce 
similar  mistakes.  The  importance  of  the  changed  intensities 
is  to  be  related  to  the  fact  that  sounds  from  in  front  are 
caught  by  the  pinna,  the  outer  ear,  and  focussed  into  the 

1  C.  S.  Myers,  Proc.  Royal  Society.     B.  vol  88,  1914;  pp.  267-284. 


328        FUNDAMENTALS   OF  PSYCHOLOGY 

meatus,  while  sounds  from  behind  are  diminished  in  volume. 
When  the  absolute  intensity  and  the  distance  of  a  sound 
are  known  or  may  be  approximated,  the  position  of  the 
sound  as  in  front  of  or  behind  the  plane  of  the  ears  can  be 
appreciated  in  terms  of  intensity.  Direction  of  sounds, 
then,  is  appreciated  by  means  of  the  relative  intensities  of 
the  tones  as  heard  by  the  two  ears,  and  by  the  timbre  and 
intensity  of  the  tone.  It  has  at  times  been  assumed  that 
direction  might  be  known  by  means  of  the  stimulation  of 
the  skin  in  the  neighborhood  of  the  ears,  or  on  other  portions 
of  the  face.  This  assumption  is  improbable  in  itself,  since 
sound  waves  are  not  sufficiently  intense  to  excite  the  organs 
of  pressure. 

The  Auditory  Space  of  the  Blind.  —  Auditory  apprecia- 
tion of  space  plays  a  much  larger  part  for  the  blind,  who 
must  trust  to  the  ears  for  a  knowledge  of  the  position  of  all 
distant  objects.  A  bUnd  man  appreciates  the  distance  of 
objects  fairly  accurately  through  the  effect  they  have  upon 
the  quahty  of  familiar  sounds,  such  as  his  footsteps  or 
the  tapping  of  his  cane.  Large  objects  reflect  the  sound, 
give  echoes,  or  modify  its  quaHty.  It  is  easy  to  distinguish 
the  difference  in  the  voice  when  speaking  in  a  room  filled 
with  people  and  when  speaking  in  an  empty  room.  Even 
the  presence  of  furniture  in  a  room  in  an  ordinary  dwelling 
has  a  pronounced  effect.  The  bUnd  man  learns  to  distin- 
guish all  of  these  differences  and  to  learn  what  they  mean 
as  to  the  presence  and  arrangement  of  objects.  That  the 
bhnd  depend  upon  the  reflection  of  sounds  in  avoiding 
objects  was  shown  by  Dr.  Heller, ^  director  of  a  blind  asy- 
lum, who  on  one  occasion  provided  his  pupils  with  felt 
slippers  in  place  of  their  heavy  shoes  and  watched  them  at 
their  play.    He  found  that  they  no  longer  avoided  obstacles 

-  Heller,  Studien  zur  blinden  Psychologic. 


OPTICAL  ILLUSIONS 


329 


and  would  come  into  conflict  with  many  of  them.  The 
sound  from  their  footsteps  could  no  longer  be  heard  suffi- 
ciently for  the  modifications  by  the  obstacles  to  be  noticed. 
It  seems,  then,  that  for  the  bhnd  much  of  the  perception  of 
space  depends  upon  the  modification  of  the  sounds  of  the 
footsteps  and  of  other  familiar  sounds,  by  walls  and  objects 

in  general. 

Illusions  in  Space  Perception 

Optical  Illusions.  —  Very  interesting  as  illustrating  the 
factors  that  lead  to  the  perception  of  space  and  of  perception 


Fig.  80.  —  Illusions  due  to  overestimation  of  the  vertical.    (From  Titchener,  op.  cit) 

in  general  are  certain  illusions  of  visual  space  perception. 
Many  more  forms  of  optical  illusion  are  known  than  we  can 
describe,  and  more  explanations  have  been  offered  than  we 
have  room  to  mention,  but  we  may  select  a  few  illusions  as 
illustrations  of  the  more  important  theories.  One  of  the 
simplest  t3^es  is  seen  in  mistaken  estimates  of  the  length 
of  lines,  or  distances  between  dots.  Thus  horizontal  lines 
seem  shorter  than  vertical  lines  of  the  same  length  (Fig.  80, 
A,  D)\  interrupted  spaces  seem  longer  than  uninterrupted 


33©        FUNDAMENTALS   OF  PSYCHOLOGY 

or  unfilled  spaces  or  lines.  Figure  8i,  A,  B,  indicates  that 
filled  space,  space  filled  with  a  number  of  dots,  or  a  solid 
line  seems  longer  than  the  empty  space  of  the  same  length; 
Figure  E,  that  a  square  with  numerous  vertical  lines  drawn 


across  it  seems  longer  than  it  is  high.  Even  these  simple 
illusions  have  given  rise  to  much  difference  of  opinion.  One 
theory  would  explain  all  in  terms  of  eye  movement.  It  is 
said  that  the  fact  that  the  up-and-down  movements  of  the 
eyes  involve  a  waste  of  effort,  owing  to  the  tendency  of 
each  superior  and  inferior  rectus  muscle  to  pull  the  eye  in 
as  well  as  up,  a  tendency  which  must  be  counteracted  by 


OPTICAL  ILLUSIONS  331 

the  oblique  muscles,  and  so  give  rise  to  greater  amounts  of 
strain,  leads  to  the  overestimation.  Experiments  made  with 
the  observer  lying  on  his  side  which  show  that  the  vertical 
distance  is  still  overestimated  would  tend  to  disprove  this 
theory.  Helmholtz  suggested  that  the  overestimation  of  the 
vertical  was  due  to  a  habit  derived  from  the  use  of  perspec- 
tive. Vertical  hnes  in  space,  as  in  a  picture,  usually  or  fre- 
quently represent  greater  horizontal  distances  seen  in 
perspective,  and  so  we  form  the  habit  of  overestimating  all 
vertical  lines. 

According  to  one  theory  the  interrupted  spaces  are  made 
to  seem  longer  by  a  similar  exaggeration  of  the  apparent 
movements  through  the  numerous  stops  that  are  made  at 
each  of  the  intervening  dots  or  lines.  That  this  is  not  the 
whole  story  can  be  seen  from  the  fact  that  where  the  dots 
are  relatively  few  (Fig.  Si,D),  one  or  two  only  in  the  length 
of  the  Hne,  the  distance  is  underestimated  rather  than  over- 
estimated. The  other  explanation  is  that  the  filled  spaces 
give  an  impression  of  multiplicity  and  this  is  confused  with 
the  length  of  the  line.  The  apparent  shortening  of  the  line 
when  only  one  or  two  dots  are  inserted  is  seemingly  due  to 
a  confusion  between  the  separate  spaces  and  the  total 
length.  The  full  line  tends  to  be  compared  with  the  smaller 
divisions  of  the  divided  line.  This  same  confusion  is  better 
illustrated  in  the  comparison  of  the  vertical  and  the  horizon- 
tal Hnes  in  Figure  80,  E.  Here  the  vertical  is  compared 
with  the  halves  of  the  base  line.  Where  erected  at  the  end 
of  the  line,  the  vertical  is  slightly  overestimated  but  rela- 
tively very  sHghtly  (Fig.  80,  D).  This  efifect  can  be  ehmi- 
nated  by  turning  the  book  ninety  degrees,  while  the  illusion 
in  E  persists. 

The  Miiller-Lyer  Illusion.  —  One  of  the  most  striking  and 
most  discussed  of  all  is  the  Miiller-Lyer  illusion.    It  will  be 


332        FUNDAMENTALS   OF  PSYCHOLOGY 

noted  that  the  Kne,  bounded  by  obHque  lines  that  turn  in, 
seems  much  shorter  than  the  other  line  of  the  same  length 
bounded  by  obHque  Hnes  that  turn  out.  The  explanations 
offered  for  this  illusion  include  practically  all  that  may  be 
offered  for  any.  Wundt  suggested  that  it  was  due  to  eye 
movements,  that  the  eyes  were  checked  too  soon  by  the 


Fig.  82.  — •  Various  forms  of  the  MiiUer-Lyer  Illusion. 

lines  that  turn  in,  and  carried  on  by  the  hnes  that  turn  out. 
It  is  suggested  that  it  can  be  explained  on  the  basis  of  per- 
spective; that  one  represents  an  open  book  or  similar  figure 
with  the  back  towards  the  observer,  the  other  an  open  book, 
much  larger,  with  covers  opened  towards  the  observer.  In 
the  first  case  the  actual  length  of  the  book  is  the  length  of 
the  fine  itself;  in  the  other,  the  length  would  be  from  the 
end  of  the  obHque  lines  at  their  greatest  separation.    Still 


OPTICAL  ILLUSIONS  7,7,7, 

another  theory  is  that  one  confuses  the  whole  spaces 
between  the  obhque  Hnes  with  the  horizontal  lines  and  really 
makes  a  judgment  of  the  spaces,  although  it  is  assumed 
that  the  lines  are  being  compared.  This  is  one  application 
of  the  so-called  theory  of  confluxion  and  contrast.  It  is 
an  instance  of  the  confluxion  phase  of  the  theory,  i.e., 


h 1 ' — 

■J —   c 

d 


Fig.  83.  —  Contrast  illusions.    (From  Titchencr,  op.  cit.) 

of  the  tendency  to  confuse  something  in  the  surroundings 
with  the  part  of  the  figure  that  is  to  be  judged. 

The  eye-movement  theory  is  in  this  case  rather  far- 
fetched. Dawes-Hicks  found  that  the  illusion  persisted 
when  the  figures  were  exposed  for  too  short  a  time  to  permit 
the  eyes  to  move.  And  while  Judd  found  that  moving 
pictures  taken  of  the  eyes  while  the  figures  are  being  com- 
pared showed  movements  that  in  many  instances  corre- 
spond to  the  illusion,  he  concluded  that  the  movements  are 


334        FUNDAMENTALS   OF  PSYCHOLOGY 


due  to  the  illusion  rather  than  the  illusion  due  to  the  move- 
ment. The  perspective  theory  serves  to  correlate  a  number 
of  different  illusions,  and  perspective  may  have  some  influ- 
ence, but  it  is  hardly  to  be  regarded  as  the  only  explanation. 


oRo 


o^o 


Fig.  84.  —  Contrast  illusions.    (From  Titchener,  op.  cit.) 

In  a  wide  sense,  the  confluxion  theory  comes  to  mean  that 
factors,  other  than  those  immediately  compared,  play  a 
part  in  determining  the  comparison,  and  in  this  form,  it 
would  include  the  perspective  element  as  well  as  any  other 


Fig.  85.  — Illusion  due  to  confluxion.    (From  Titchener,  op.  cit.) 

considerations  which  might  aid  in  controlKng  the  judgment. 
On  the  whole  it  more  nearly  corresponds  to  the  facts. 

Illusions  of  size  that  illustrate  the  effect  of  contrast  are 
seen  in  the  lines  of  Figure  83  and  the  circles  of  Figure  84. 


OPTICAL  ILLUSIONS 


335 


The  distance  between  two  short  hnes  seems  much  longer 
than  one  of  the  same  length  between  two  long  lines.  Much 
the  same  effect  is  obtained  with  the  circles.  In  Figure  85, 
when  the  two  circles  are  put  together  to  form  a  band,  the 
one  seems  larger,  the  other  smaller,  than  when  separate. 
When  together,  the  observer  confuses  each  with  the  center 
of  the  ring,  and  so  tends 
to  judge  each  as  the  aver- 
age between  them  (con- 
fluxion).  When  a  circle 
is  surrounded  by  a  series 
of  very  small  circles,  its 
size  seems  to  increase  as 
compared  with  the  same 
circle  near  a  single  much 
larger  one  (contrast). 
(Fig.  84.) 

Angle  Illusions.  —  Illu- 
sions of  direction  are  also 
numerous.  They  may  be 
illustrated  by  the  Zollner 

illusion  (Fig.  86),  the  Hering  figure,  the  Wundt  figure  (Fig. 
87,  ^  and  5),  and  the  Poggendorf  figure  (Fig.  88).  The 
eye-movement  theory,  the  perspective  explanation,  and  con- 
fluxion  have  all  been  used  as  explanations.  The  eye-move- 
ment theory  holds  that  the  eyes  are  distracted  by  the  cross 
lines;  but  why  they  should  be  is  not  made  particularly  clear. 
The  perspective  theory  may  take  two  forms.  Each  of  the 
first  three  figures  may  be  seen  as  if  drawn  in  perspective ;  and^ 
inasmuch  as  the  parallel  lines  do  not  converge  as  they  should 
to  harmonize  with  the  perspective,  it  is  assumed  that  they 
must  diverge.  Still  another  appHcation  is  that  the  whole 
figures  may  be  explained  as  due  to  the  overestimation  of 


■  Zollner  "s  Illusion. 
ener,  op.  cit.) 


(From  Titch- 


336        FUNDAMENTALS   OF  PSYCHOLOGY 

acute  angles  and  the  underestimation  of  obtuse  angles.  It 
will  be  seen  that  this  is  what  really  happens  in  each  case. 
But  it  may  be  said,  in  addition,  that  the  estimation  of  the 


Fig.  87.  —  Hering's  and  Wundt's  figures.     (From  Titchencr,  op.  .-it.) 

angles  is  made  on  the  assumption  that  whenever  two  lines 
cross  at  right  angles  and  are  distorted  by  perspective,  the 
figure  represents  two  lines  crossing  at  right  angles  as  seen 
with  the  horizontal  line  in  an  oblique  plane.  This  can  be 
made  out  in  Figures  89  and  90,  where  the  two  lines  can 


THEORIES   OF   SPACE 


337 


easily  be  imagined  to  represent  two  lines  crossing  at  right 
angles.  Since  all  angles  made  by  straight  lines  are  likely  to 
indicate  right  angles  seen  in  perspective,  we  have  acquired 
the  habit  of  overestimating  acute  and 
underestimating  obtuse  angles.  The 
Poggendorf  illusion  readily  falls  under 
this  explanation.  The  lines  do  not 
meet,  because  each  is  turned  toward  the 
horizontal;  and  they  are  turned  toward 
the  horizontal  by  the  overestimation  of 
the  small  angles;  or  to  go  back  to  the 
explanation  of  that  tendency,  one  in- 
clines to  see  it  as  if  it  were  really  more 
nearly  perpendicular  to  the  vertical  line. 

These  illusions,  then,  are  all  due  to 
the  fact  that  interpretation  tends  to 
become  mixed  with  sensation,  and  that 
one  cannot  keep  attention  fixed  exclu- 
sively upon  the  essentials  of  the  figure, 
but  is  misled  by  its  surroundings.  Mixed 
with  the  confusion  of  part  with  the 
whole,  we  always  find  the  tendency  to 
see  what  the  figure  means  rather  than 
the  figure  itself,  and  to  beheve  that  it  means  something 
different  from  what  it  actually  represents.  The  various 
special  theories,  perspective,  confusion,  or  confluxion,  even 
eye  movements,  are  but  special  forms  of  this  general 
tendency. 

General  Theories  of  Space  Perception.  —  A  more  ab- 
stract problem  naturally  arises  at  the  end  of  a  statement  of 
the  particular  facts  of  space  perception,  —  the  question, 
what  is  the  idea  of  space  itself.  Two  schools  have  contended 
over  this  question  since  the  beginnings  of  modern  philoso- 


FiG.  88.  — Poggen- 
dorf's  Illusion.  (From 
Titchener,  ol>.  cit.) 


338        FUNDAMENTALS   OF  PSYCHOLOGY 

phy.  One,  the  nativistic  school,  insists  that  the  capacity  to 
appreciate  space  is  born  with  us,  and  may  be  used  without 
preliminary  practice.  It  may  be  dependent  upon  inherited 
characteristics  of  our  nervous  system,  or  may  be  an  original 
mental  activity.  The  other  school,  the  empirical,  asserts 
that  the  notion  of  space  is  developed  through  experience, 
—  must  be  derived  in  some  way  from  the  conditions  of 


Fig.  89.  —  Hering's  angle  illusions.  Careful  observation  shows  that  any  of  the 
oblique  lines  may  be  interpreted  as  crossing  in  some  other  than  the  plane  of  the 
page.    (From  Titchener,  op.  cit.) 

perception.  For  the  nativist,  space  offers  no  problems;  it 
is  appreciated  at  once,  as  color  is  appreciated.  For  the 
empiricist,  it  is  necessary  to  discover  the  components  of  the 
space  idea  and  also  to  determine  how  a  particular  space  idea 
is  suggested.  The  concrete  evidence  for  neither  position  is 
conclusive.  The  empiricists  point  to  the  numerous  cases 
of  error  in  judgment,  and  the  cases  in  which  appreciation  of 
space  may  be  shown  to  depend  upon  definite  sensations  and 
particular  associations.  The  nativist  contents  himself  with 
the  statement  that  the  factors  which  according  to  the  em- 


THEORIES  OF  SPACE 


339 


piricist  compose  space  are  altogether  different  from  space 
as  we  know  it,  and  also  that  it  is  inconceivable  that  space 
can  be  derived  from  anything  not  itself  spatial. 

The  Space  Discrimination  of  Those  Born  Blind.  —  The 
problem  cannot  ordinarily  be  approached  directly,  since 
the  child  has  already  developed  his  notion  of  space  before 
he  is  able  to  tell  us  about  it,  and  adults 
when  questioned  will  have  long  forgot- 
ten what  their  first  experiences  were 
like  and  how  they  developed  spatial 
ideas.  As  early  as  the  seventeenth  cen- 
tury, Locke  suggested  that  if  one  could 
find  a  man  who  had  been  born  blind 
and  recovered  his  sight  after  he  became 


DRIVE 
SLOWLY 

,  ,  ,  •,      1  •  •  .  11         ^'^-  90-  —The  trans- 

able  to  describe  his  experiences,  it  would    formation  of  right  an- 

be  possible  to  say  how  much  of  space  J/J;  pXeclivt'"'' 
perception  was  innate  and,  if  it  proved 
not  to  be  innate,  how  it  was  acquired.  Since  then  a  fair 
number  of  cases  of  this  sort  have  been  observed.  The 
lens  of  the  eye  is  occasionally  opaque  from  birth  and  may 
be  removed  by  an  operation,  and  the  patient  be  made  to 
see.  There  is  no  great  agreement  as  to  what  the  patient 
can  see,  but  the  following  statements  seem  to  be  in 
harmony  with  most  results.  The  shape  of  objects  is 
not  recognized  at  all.  One  patient  could  not  tell  a 
square  from  a  circle  untJl  he  had  had  a  chance  to  touch 
each.  The  field  of  vision  is  described  as  a  confused 
mass  in  which  everything  seems  to  be  in  irregular  move- 
ment. Some  patients  are  said  to  notice  the  difference  be- 
tween geometrical  figures  when  they  cannot  say  in  what 
that  difference  consists.  One,  after  being  told  what  an  an- 
gle was,  could  count  the  angles  on  a  figure  and  thus  distin- 
guish a  triangle  from  a  square,  but  for  some  time  after- 


340        FUNDAMENTALS  OF  PSYCHOLOGY 

wards  was  not  able  to  distinguish  without  this  counting. 
The  perception  of  distance  was  defective  in  each  instance. 
Objects  seemed  in  most  cases  to  touch  the  eye,  and  in  no 
case  were  they  projected  beyond  the  reach  of  the  patient. 
There  is  practically  no  appreciation  of  depth.  When  all 
the  evidence  has  been  assembled,  neither  school  is  alto- 
gether convinced  of  the  falsity  of  its  own  position.  The 
nativist  argues  that  the  patient  sees  so  Uttle,  because  he 
transfers  the  associations  developed  by  touch  to  sight.  The 
patient  thinks  objects  must  touch  his  eyes  because  they 
touch  his  skin.  The  empiricist,  on  the  contrary,  argues 
that  the  patient  would  see  nothing  were  it  not  for  this 
same  earUer  experience,  that  interpretation  from  tactual 
experiences  and  from  the  light  that  comes  through  the 
lenses  before  the  operation  makes  possible  even  such  im- 
perfect spatial  judgments  as  are  made. 

The  attempts  made  by  the  empiricist  to  explain  or  an- 
alyze the  spatial  experience  have  for  the  most  part  con- 
sisted in  reducing  the  various  forms  into  some  single  one. 
Movements  or  memories  of  movements  are  most  frequently 
asserted  to  constitute  the  essential  idea  of  space.  Double 
images,  according  to  the  theory,  give  an  i'dea  of  depth  be- 
cause they  call  up  the  memories  of  old  movements  ^  con- 
vergence or  of  the  reaching  movements  required  to  obtain 
the  object.  That  such  transfers  from  one  sense  to  another 
do  take  place  is  readily  observed.  Most  persons  use  a 
visual  space,  although  a  motor-minded  individual  may 
translate  visual  and  tactual  distances  into  kinaesthetic 
terms.  But,  after  all,  translation  from  one  space  to  an- 
other does  not  solve  the  problem  of  space.  No  one  sense 
gives  a  more  direct  and  intuitive  knowledge  of  space  than 
any  other.  Vision  is  probably  more  dehcate  in  its  appre- 
ciation, while  movement  demands  an  accuracy  in  space  es- 


THEORIES    OF   SPACE  341 

timates  to  be  adequate;  but  it  cannot  be  said  that  the  ac- 
curacy of  the  one  or  the  needs  of  the  other  constitute  it 
the  intuitive  space  sense. 

We  may  reduce  the  problem  of  the  origin  of  space  to  its 
lowest  terms,  if  we  see  that  there  are  three  essential  ele- 
ments in  the  spatial  experience.  These  are  the  sensation 
or  sensory  cue,  the  idea  or  notion  of  space,  and  the  associa- 
tion between  them.  Some  sensory  cue  must  always  be 
present  to  suggest  the  idea.  Contact  on  a  spot  calls  up 
the  idea  of  position;  double  images,  strains  of  accommo- 
dation and  convergence  arouse  the  idea  of  distance.  The 
question  as  to  what  is  innate  and  what  derived  from  ex- 
perience, may  be  considered  separately  for  each  of  these 
cases.  We  may  assert  at  once  that  the  connection  is  de- 
rived through  experience.  Illusions  show  that  the  asso- 
ciates may  be  misplaced  —  the  wrong  idea  may  be  called 
up  by  any  cue  —  and  an  innate  capacity  to  make  mis- 
takes is  not  desired  by  the  most  ardent  supporters  of  a 
nativist  theory. 

That  the  exciting  cause  of  all  perception,  a  bare  sensa- 
tion or  sensory  stimulus,  depends  upon  the  physical  struc- 
ture of  the  sense  organ  or  the  nervous  connections,  and  to 
this  extent  is  innate,  no  one  will  deny.  The  case  for  the 
idea  is  not  so  clear.  Whether  this  be  innate  or  derived  is 
the  real  crux  of  the  problem.  The  argument  that  it  is  de- 
rived must  give  over  any  attempt  to  reduce  it  to  a  single 
element  or  even  to  a  combination  of  different  elements 
which  preserve  their  original  character.  Space  cannot  be 
movement,  it  cannot  be  sight  or  touch.  Judd  has  sug- 
gested that  it  is  not  a  movement  but  an  organized  system 
of  movements  in  which  the  various  contradictions  have 
been  removed  and  suited  to  all  possible  occasions  for  ac- 
tion. 


342        FUNDAMENTALS   OF  PSYCHOLOGY 

Space  an  Integrating  Concept.  —  If  we  accept  this  state- 
ment as  far  as  it  goes,  we  must  add  to  it  that  space  is  an 
organization  of  experience  as  a  whole,  sensory  as  well  as 
motor;  and  that  there  results  from  it  not  movement,  but 
a  concept  or  notion  which  not  merely  prepares  for  action 
but  makes  it  possible  to  represent  all  spatial  experiences 
consistently  and  harmoniously.  We  may  use  it  for  our  es- 
timates of  space,  as  well  as  in  the  control  of  movements, 
—  for  the  combinations  of  the  mathematician  as  well  as 
for  the  actual  structures  of  the  engineer.  What  the  actual 
content  of  this  idea  is  cannot  be  asserted.  Like  most  con- 
cepts, it  is  more  important  for  the  things  it  represents  than 
for  itself.  It  probably  varies  in  many  respects  from  indi- 
vidual to  individual.  It  is  certainly  more  highly  devel- 
oped for  the  mathematician  than  for  the  common  man, 
and  more  highly  developed  for  the  adult  than  for  the  child, 
for  the  civihzed  man  than  for  the  savage.  The  process  of 
development  has  probably  been  to  accept  some  simple  idea 
or  even  sensation,  and  to  use  it  until  contradictions  ap- 
pear. These  contradictions  are  obviated  by  changing  the 
notion  until  something  that  avoids  the  difficulties  is  hit 
upon,  and  this  is  again  changed  as  occasion  arises.  The 
concept  always  grows  out  of  practical  needs,  whether  sen- 
sory or  motor.  Thus  images  on  the  retina  are  given  a  size 
that  can  be  most  readily  fitted  into  our  conception  of  the 
field  of  vision  as  a  whole.  Small  objects  are  usually  seen 
as  if  they  were  at  about  arm's  length  or  where  they  can  be 
easily  manipulated,  houses  at  a  distance  that  gives  us  a 
good  view  of  them;  and,  in  thought,  these  various  typical 
distances  or  sizes  are  used  in  place  of  the  sizes  of  the  im- 
ages on  the  retina.  They  are  what  are  called  the  real  sizes 
of  the  objects.  Similar  notions  develop  for  position,  for 
extent,  and  for  depth.     They  are  changed  and  adjusted 


THEORIES   OF   SPACE  343 

until  they  satisfy  the  conditions  of  movement,  of  sight, 
and  touch,  and  of  the  practical  and  theoretical  needs  of 
every  sort.  In  the  final  concept,  little  if  any  trace  of  the 
particular  ideas  need  be  left,  certainly  nothing  that  can  be 
analyzed  out  of  the  concept  by  direct  introspection.  It 
represents  the  various  experiences  as  corrected  by  different 
tests,  but  it  is  not  compounded  out  of  them.  Our  choice 
as  to  the  real  nature  of  space  lies  between  these  alterna- 
tives: the  assumption,  on  the  one  hand,  that  it  is  a  con- 
cept that  has  developed  out  of  experience  by  innumerable 
trials  that  finally  give  rise  to  a  system  of  ideas  which  sat- 
isfactorily represents  space;  and  on  the  other  hand,  the 
nativist  position,  that  an  appreciation  of  space  is  given 
once  and  for  all,  and  that  we  certainly  cannot  explain  it; 
we  can  at  most  watch  its  development.  The  former  ex- 
planation seems  to  the  writer  to  offer  the  possibility  of  a 
real  explanation;  the  latter  gives  up  the  problem  as  in- 
soluble. 

REFERENCES 

James:  Principles  of  Psychology,  Vol.  II,  pp.  134-282. 
Ladd-Woodworth  :     Principles    of    Physiological    Psychology, 

pp.  380-469. 
Witasek:  Raumwahrnehmung. 
Bourdon:  La  Perception  visuelle  de  Tespace. 
Helmholtz:  Physiologische  Optik.,  Vol.  III. 


CHAPTER  XI 

PERCEPTION  {Continued) 

Perception  of  Movement 

Visual  Perception  of  Movement.  —  How  the  eye  appre- 
ciates movement  is  a  problem  closely  related  to  the  percep- 
tion of  space;  in  many  ways  it  is  intermediate  between 
the  perception  of  space  and  of  time.  Two  forms  of  move- 
ment must  be  distinguished:  one  in  which  the  movement 
can  be  actually  seen;  and  a  second  in  which  movements 
are  so  slow  that  one  infers  that  the  object  has  moved  from 
the  fact  that  its  position  changes  between  two  observa- 
tions. The  movement  of  a  meteor  belongs  in  the  first 
class;  that  of  the  sun  in  the  second.  The  slowest  rate 
that  can  be  really  seen  is  one  angular  minute  per  second. 
Movements  may  also  be  too  fast  to  be  seen  directly.  An 
electric  spark  moving  more  than  15"  in  a  thousandth  of  a 
second  cannot  be  seen  to  move.  Nothing  more  is  seen 
than  the  path.  Three  different  theories  of  how  we  per- 
ceive the  intermediate  rate  may  be  mentioned.  The  first 
holds  that  the  eye  follows  the  moving  object,  and  that  ap- 
preciation of  the  movement  of  the  eye  gives  also  a  knowl- 
edge of  the  movement  of  the  object.  This  theory  is  very 
direct,  but  depends  for  its  acceptance  upon  proof  of  abihty 
to  appreciate  the  movement  of  the  eye  muscles.  Recently, 
various  bits  of  evidence  indicate  that  movements  of  the 
eye  muscles  are  much  less  accurately  known  than  has  been 
sometimes  assumed.  In  the  first  place,  there  is  httle  ac- 
curacy in  estimating  the  movement  of  an  object  when  it 

344 


VISUAL  PERCEPTION  OF   MOVEMENT       345 

stands  alone  in  the  field  of  vision.  A  faint  light  moving  in 
the  dark  may  seem  to  move  much  more  slowly  than  it 
really  does;  and,  on  the  contrary,  a  stationary  Hght  in  the 
dark  may  seem  to  be  moving.  If  two  faint  lights  are  at- 
tached to  the  ends  of  a  rod  revolving  about  a  point  near  its 
middle,  the  appreciation  of  the  movements  is  uncertain. 
Either  light  may  seem  to  move,  while  the  other  is  station- 
ary, or  the  motion  may  be  divided  between  them  in  any 
proportion.  When  only  two  hghts  are  in  the  field,  one 
sees  the  relative  but  not  the  absolute  motion.  When  sta- 
tionary objects  are  in  the  field,  it  seems  that  the  move- 
ment of  objects  is  determined  by  their  relation  to  the  fixed 
objects  in  the  field  of  view,  rather  than  by  following  the 
object  with  the  eye,  and  appreciating  the  movement 
through  the  contraction  of  the  muscles. 

The  After-image  Theory.  —  Stern,  among  many  other 
writers,  has  suggested  a  second  theory,  —  that  movements 
are  appreciated  through  the  after-images  which  the  mov- 
ing object  leaves  upon  the  retina.  Watch  any  object  in 
fairly  rapid  motion  and  you  will  notice  that  it  leaves  a 
trail  of  after-images  as  it  moves  and  that  its  course  can  be 
distinctly  made  out  for  a  few  moments  by  means  of  this 
trail.  The  motion  of  the  moving  picture  is  due,  on  this 
theory,  to  the  fact  that  the  separate  pictures  of  the  object 
also  leave  a  line  of  after-images  and  that  these  are  inter- 
preted to  mean  motion.  The  motion  seems  continuous  if 
the  separate  images  succeed  each  other  with  an  interval  of 
no  more  than  fifteen  thousandths  of  a  second,  a  rate  much 
higher  than  that  ordinarily  used  in  exhibitions,  fifteen  to 
twenty  per  second.  This  theory  may  be  applied  to  ex- 
plain the  differences  between  the  three  kinds  of  motion: 
movements  too  slow  to  be  seen  must  leave  no  after-image 
that  can  be  noticed;    while  in  movements  too  fast  to  be 


346        FUNDAMENTALS   OF  PSYCHOLOGY 

seen,  no  distinction  can  be  made  between  the  after-image 
and  the  primary  stimulation,  the  whole  course  is  of  ap- 
proximately the  same  intensity;  only  when  the  after-images 
actually  outline  the  path  of  the  moving  object  on  the  ret- 
inas, in  motion  of  moderate  rate,  do  we  actually  see  move- 
ment. The  trail  of  after-images  also  affords  a  means  of 
determining  the  course  of  the  motion.  It  is  more  intense 
near  the  stimulus  and  becomes  gradually  fainter  the  greater 
the  distance  from  the  stimulus.  After-images,  then,  are 
interpreted  as  motion,  and  the  direction  of  the  motion  is 
assumed  to  be  from  faint  to  vivid  images. 

After-images  of  Movement.  —  That  motion  itself  has  an 
after-image  is  an  important  fact  for  the  theories  of  move- 
ment, and  its  study  has  contributed  much  to  the  explana- 
tion of  movement  in  general.  If  one  look  for  several  sec- 
onds at  any  moving  surface,  the  paper  on  a  kymograph,  a 
stream,  or  at  a  revolving  spiral,  and  then  look  away  at  a 
stationary  surface,  there  will  seem  to  be  a  movement  in 
the  opposite  direction.  Two  explanations  of  this  phe- 
nomenon have  been  offered;  that  it  is  due  to  the  reversal 
of  the  after-image,  and  that  it  is  due  to  an  actual  displace- 
ment of  retinal  elements  by  the  motion,  followed  by  their 
return  to  the  original  position  when  the  movement  ceases. 
Visual  after-images  change  from  positive  to  negative 
shortly  after  the  stimulus  is  removed,  as  will  be  remem- 
bered from  an  earlier  chapter.  If  in  the  original  motion 
the  after-images  near  the  object  are  dark,  and  the  more 
remote  are  brighter,  in  the  negative  after-image  the  dark 
portion  becomes  bright,  and  so  the  more  remote  parts  will 
appear  brighter.  The  negative  after-image  of  brightness 
accounts  for  the  apparent  reversal  of  the  movement. 

The  Theory  of  Retinal  Streaming.  —  That  the  percep- 
tion of  movement  and  the  reversal  of  direction  in  the 


VISUAL  PERCEPTION  OF   MOVEMENT       347 

after-image  are  due  to  actual  movement  of  elements  in 
the  retina  has  been  asserted  for  some  time  and  has  been 
strongly  supported  recently  by  Ferree  and  Hunter.  This 
is  our  third  theory  of  the  perception  of  movement.  The 
evidence  in  its  favor  is  the  great  vividness  and  persistence 
of  the  sensory  processes,  particularly  in  the  after-image  of 
movement.  These  observers  assert  that  when  the  after- 
image of  motion  is  well  developed,  there  seems  to  be  a 
veil  of  objects  streaming  over  any  surface  looked  at,  and 
that  it  would  be  impossible  for  after-images  or  any  of  the 
other  factors  suggested  to  persist  long  enough  or  be  suf- 
ficiently realistic  to  account  for  the  effect  noticed.  On  the 
other  hand,  they  admit  that  what  we  know  of  the  retinal 
structure  gives  no  evidence  in  favor  of  an  actual  movement 
of  its  elements.  Altogether  the  after-image  theory  seems 
more  plausible.  After-images  are  known  to  exist  and 
must  aid  in  the  perception  of  motion.  The  'only  question 
is  whether  they  account  for  all  of  the  observed  phenomena. 
We  may  at  least  accept  the  after-image  theory  as  the  most 
probable  at  present  for  the  explanation  of  all  perception 
of  movement. 

Considering  the  problem  of  how  we  see  movement  at  all 
to  be  settled,  it  is  still  necessary  to  consider  how  we  distin- 
guish between  possible  interpretations  in  actual  movements. 
Many  of  the  phenomena  may  be  the  result  of  several  dif- 
ferent conditions  in  the  outer  world.  Either  the  eye  or  the 
field  of  vision  may  be  in  motion  when  many  objects  are 
leaving  after-images.  We  may  distinguish  three  conditions 
of  motion,  if  we  consider  only  the  movements  of  objects 
and  of  the  eyes.  The  eye  may  be  stationary  and  one  ob- 
ject in  motion;  the  eye  may  be  in  motion,  following  one 
object,  perhaps,  while  the  rest  of  the  field  is  stationary; 
or,  finally,  the  eye  may  be  following  one  object  while  other 


348        FUNDAMENTALS   OF  PSYCHOLOGY 

objects  are  moving  in  different  directions  or  at  different 
rates. 

The  first  case  has  been  discussed  above.  In  the  second 
case,  one  would  have  a  clear  image  of  the  object  that  was 
pursued  by  the  eye,  while  all  other  objects  would  be  seen 
in  blurred  images  or  would  be  leaving  after-images.  Here 
we  must  explain  how  we  know  that  the  eye  is  moving. 
This  might  be,  either  through  the  sensations  from  the  eye 
muscles,  or  by  the  after-images,  or  other  signs  of  move- 
ment developed  on  the  retina  by  stationary  objects.  The 
clear  image  of  the  object  in  flight  would  show  that  it  was 
being  properly  followed,  while  the  after-images  of  all  other 
objects  serve  as  an  indication  of  the  movement  of  the  eye. 

Still  more  complicated,  but  nevertheless  capable  of  ex- 
planation along  the  same  lines,  is  the  problem  offered  when 
the  object  and  eye  are  in  motion  in  different  directions  or 
at  different  rates.  Here  the  total  estimate  is  based  on  a 
comparison  of  the  movement  of  the  eye  with  the  displace- 
ment of  the  image.  In  each  of  these  cases  much  depends 
upon  the  estimate  of  the  probabiUty  of  movement.  Even 
when  it  is  a  question  whether  the  motion  is  of  the  external 
object  or  of  the  observer,  interpretation  is  important.  If 
one  stands  on  a  bridge  over  a  rapidly  running  stream,  it 
is  quite  easy  to  ascribe  the  motion  to  thfe  bridge.  The 
probabihties  in  the  Hght  of  frequency  of  occurrence  are 
that  a  small  object  Hke  a  bridge  will  be  in  motion  rather 
than  the  larger  river.  Similarly,  when  you  are  on  one  of 
two  trains  standing  in  a  station,  and  one  starts,  motion  is 
ascribed  to  one  or  the  other  in  accordance  with  your  ex- 
pectations. Not  merely  the  sensory  elements  that  give 
the  perception  of  motion  must  be  taken  into  account,  but 
also  the  estimation  through  early  experience  of  the  prob- 
ability that  the  object  is  or  is  not  likely  to  move. 


THE   NATURE   OF  RHYTHM  349 

REFERENCES 

Ferree:  The    Streaming    Phenomenon,    Amer.    Jour.    Psych., 

Vol.  19. 
Hunter:  Retinal  Factors  in  Visual  After-Movement,  Psychol. 

Rev.,  Vol.  22,  p.  479. 
Wohlgemuth:  On   the  After-Effects  of  Visual  Motion,   Brit. 

Journal  of  Psychology,  Monograph  Suppl.  I. 

RfeYTHM 

Most  series  of  excitations  vi^hich  repeat  themselves  at 
short  intervals  tend  to  fall  into  rhythm.  Rhythm  needs 
no  description,  and  one  could  not  be  given  if  demanded. 
Two  factors  may  be  distinguished  in  rhythm,  the  grouping 
of  the  single  elements  into  units,  and  the  accenting  or  em- 
phasizing of  one  or  more  of  the  units.  Auditory  and  kinaes- 
thetic  impressions  show  rhythm  most  easily;  tactual  and 
visual,  not  so  markedly.  The  accentuation  in  rhythm  may 
be  produced  in  a  number  of  different  ways  all  of  which 
give  the  same  effect.  It  can  be  given  subjectively  as  well 
as  objectively.  If  one  listen  to  the  ticking  of  a  clock  or 
the  beats  of  a  metronome,  it  will  be  noticed  that  they  tend 
to  form  units,  and  that  the  character  of  the  unit,  the  sound 
that  is  accented,  will  vary  from  time  to  time,  and  within 
limits,  can  be  changed  at  will.  Objectively,  it  is  possible 
to  emphasize  one  unit  in  the  measure,  either  by  increasing 
the  intensity  of  the  note  to  be  accented,  or  by  increasing 
the  length  of  the  note.  This  is  evidenced  by  a  comparison 
of  ancient  with  modern  verse.  While  the  former  produced 
its  rhythmic  effect  by  lengthening  the  syllable,  English 
poetry  obtains  the  same  effect  by  increasing  the  intensity 
of  the  syllable.  A  similar  difference  in  the  way  of  produc- 
ing effects  can  be  seen  in  music  of  the  organ  and  of  the 
piano.    On  the  organ  the  intensity  is  constant,  rhythm  is 


350        FUNDAMENTALS  OF  PSYCHOLOGY 

obtained  by  increasing  the  duration  of  a  tone,  while  on  the 
piano,  accent  is  given  by  increasing  the  intensity  of  the 
note.  The  rhythm  is  the  same  in  both  cases.  In  fact,  men 
who  have  played  the  organ  for  years  often  do  not  notice 
either  the  difference  in  the  effect  or  in  the  way  in  which  it 
is  produced.  Not  only  may  accent  be  given  by  changing 
the  character  of  the  note,  but  also  by  changing  the  inter- 
vals between  the  notes.  In  a  measure  of  three  notes  of 
the  same  intensity  and  duration,  if  the  first  interval  be  in- 
creased, the  first  note  will  be  accented;  if  the  second  in- 
terval be  increased,  the  last  note  will  be  accented. 

The  way  in  which  groups  are  formed  in  regularly  recurrent 
sensations  may  also  be  reduced  to  certain  laws.  The  more 
rapid  the  rate  of  succession,  the  greater  the  number  that 
may  be  brought  into  a  single  unit.  In  very  rapid  beats  of 
the  metronome,  two  hundred  per  minute  or  so,  it  is  possible 
to  combine  as  many  as  eight  beats  in  a  single  unit.  The 
size  of  the  unit  may  be  varied  at  will  within  hmits.  When 
they  are  sixty  or  less  per  minute,  it  is  with  difficulty  that 
two  may  be  grouped.  In  general,  Woodrow  found  that  in 
a  series  of  tones  separated  by  equal  intervals  in  which  every 
other  note  or  every  third  was  more  intense,  the  group  would 
begin  with  the  more  intense  tone.  When  intensities  were 
equal  but  alternate  notes  were  longer,  the  longer  note  would 
start  the  measure.  The  grouping  and  the  accent  depend 
upon  both  objective  and  subjective  factors. 

The  Theories  of  Rhythm.  —  Two  theories  to  explain  these 
various  facts  of  rhythm  are  at  present  current.  One  is  that 
rhythm  has  a  motor  origin,  that  the  impulse  to  beat  time  is 
universal,  and  that  any  external  series  that  will  call  out  this 
tendency  produces  the  rhythm.  Genetically,  it  is  argued 
that  rhythmic  movements  are  inseparable  from  bodily 
activity,  that  the  movements  in  physical  labor  came  to  take 


PERCEPTION  OF  RHYTHM  351 

on  a  rhythmic  form,  and  this  may  have  been  transformed 
into  the  dance,  which  in  primitive  races  is  frequently  derived 
from  the  daily  work,  and  that  it  then  was  introduced  into 
music  and  reached  its  present  degree  of  complexity. 

The  other  theory,  based  on  attention,  develops  from  the 
fact  that  most  of  the  factors  which  induce  accentuation 
also  give  rise  to  attention.  Both  intensity  and  length  of 
stimulus  were  found  among  the  objective  conditions  of 
attention.  More  striking  is  the  evidence  from  the  effects 
of  the  preceding  and  succeeding  interval.  A  period  of  expec- 
tation is  an  important  factor  in  arousing  attention.  Where 
a  note  in  the  rhythmic  group  has  been  preceded  by  an  inter- 
val, expectation  increases  regularly  during  the  prehminary 
wait;  and  when  the  stimulus  finally  makes  its  appearance, 
it  is  more  fully  attended  to  and  seems  more  intense  than 
impressions  that  have  been  preceded  by  the  shorter  interval. 
Less  obvious  is  the  explanation  of  the  effect  when  a  longer 
interval  succeeds  the  stimulus.  This  seems  to  offer  oppor- 
tunity for  full  attention  to  the  effect  of  the  stimulus  after 
it  has  stopped,  and  this  is  supposed  also  to  increase  its 
apparent  intensity.  It  seems  probable,  from  observation 
and  particularly  from  the  fact  that  an  interval  affects  the 
accent  of  the  note  that  preceded,  that  the  appreciation  of 
the  rhythmic  unit  takes  place  at  the  end  of  the  measure. 
The  unit  is  heard  as  a  whole  at  the  moment  it  is  completed 
rather  than  bit  by  bit  as  each  impression  comes  to  conscious- 
ness. The  attention  theory,  then,  would  hold  that  rhythm 
is  induced  by  any  circumstance  that  makes  some  one  or 
more  elements  in  the  series  of  tones  occupy  a  more  impor- 
tant place  in  consciousness  than  the  others,  and  that  the 
whole  group  becomes  a  unit  for  attention. 

While   the   attention    theory  has   some   advantages   in 
explaining  why  the  emphasis  comes  as  it  does,    it  seems 


352        FUNDAMENTALS   OF  PSYCHOLOGY 

probable  that  a  considerable  portion  of  the  sensory  content 
of  the  rhythm  is  supphed  by  the  motor  contractions  which 
may  come  as  a  result  of  the  subjective  accentuation.  A 
good  case  can  be  made  for  either  theory,  and  they  are  not 
at  all  contradictory  or  out  of  harmony  one  with  the  other. 

REFERENCE 

WOODROW:    A   Quantitative    Study   of  Rhythm:    Archives   of 
Psychology,  No.  14. 

Perception  of  Time 

Problems  Concerning  Time.  —  Time  offers  many  of  the 
same  problems  as  space.  It,  too,  is  a  universal  characteris- 
tic of  all  our  experience,  and  there  has  been  the  same  dis- 
cussion as  to  whether  it  has  real  existence  or  is  merely 
subjective.  As  with  space,  we  may  ask  how  short  a  time 
can  be  noticed,  and  how  we  appreciate  longer  intervals. 
The  traditional  question,  how  short  a  time  may  be  expe- 
rienced, receives  a  different  answer  for  each  of  the  senses 
and  combinations  of  senses.  It  is  much  shorter  for  hearing 
(.002)  than  for  sight  (.044)  and  may  rise  to  0.16  second  when 
one  stimulus  is  given  by  sight,  the  other  by  the  ear.  When 
one  turns  to  a  study  of  the  longer  times,  it  is  found  that  the 
estimation  of  time  and  even  our  awareness  of  the  passage 
of  time  vary  greatly  with  the  duration  of  the  intervals 
involved.  If  one  is  asked  to  listen  to  times  of  different 
length,  certain  times  are  at  once  pronounced  very  short, 
too  short  to  be  perceived  with  comfort,  others  as  too  long 
to  be  easily  appreciated.  Times  under  5500-  (a-  means 
thousandths  of  a  second)  seem  too  short,  are  hurried,  and 
not  adequately  comprehended.  On  the  other  hand,  times 
over  about  1800  <t  seem  very  long,  and  it  is  with  difficulty 
that  they  can  be  brought  within  the  span  of  comprehension. 


PERCEPTION   OF  TIME  353 

At  about  four  seconds,  it  is  no  longer  possible  to  bring  the 
events  within  a  single  compass;  one  reaches  the  limit  of  a 
single  span  of  time  so  far  as  it  can  be  experienced.  It 
should  be  noted  that  this  is  also  approximately  the  length 
of  the  primary  memory.  Within  this  period  events  may 
be  held  in  a  single  span  of  memory,  and  the  memory  image 
can  be  used  with  the  same  care  and  certainty  as  a  sensation. 
It  is  by  virtue  of  this  fact  that  it  is  said  to  constitute  the 
immediately  experienced  present. 

The  Different  Ways  of  Perceiving  Time.  —  The  point 
of  division  between  the  hurried  and  the  comfortable  time 
is  of  interest  for  another  reason.  It  is  found  that  if  one 
attempts  to  compare  times  under  0.6-0.75  second,  there 
is  always  a  tendency  to  overestimate  the  first;  while  similar 
comparisons  of  times,  greater  than  this  indifference  time, 
lead  to  the  underestimation  of  the  first.  This  time  ap- 
proximately coincides  with  the  point  of  division  between 
the  times  felt  as  very  short  and  those  which  seem  of  moder- 
ate duration,  and  furnishes  additional  evidence  that  there 
is  a  real  difference  in  the  means  of  estimating  times  above 
and  below.  Some  light  may  be  thrown  upon  the  conditions 
of  the  perception  of  time  by  a  study  of  the  factors  that 
influence  the  comparison  of  intervals.  First,  anything 
that  influences  expectation  is  important.  Thus,  if  sounds 
are  separated  by  equal  intervals  and  every  alternate  note 
is  more  intense,  the  interval  that  precedes  the  more  intense 
sound  will  seem  to  be  lengthened.  This  has  been  explained 
as  due  to  the  surprise  induced  by  the  strong  tone,  which 
increases  the  strain  ascribed  to  the  preceding  interval. 

The  filling  of  an  interval  also  influences  its  appreciation. 
With  short  times  it  is  found  that  filled  time  seems  longer 
than  empty.  If  the  time  be  longer,  and  one  be  permitted 
to  read  during  one  period  and  to  do  nothing  during  the  other, 


354        FUNDAMENTALS   OF  PSYCHOLOGY 

the  time  spent  reading  seems  shorter  than  the  empty.  The 
probable  explanation  of  the  latter  difference  is  to  be  found 
in  the  fact  that  the  empty  time  is  really  filled  by  noticing 
strains  and  other  internal  sensations,  while,  during  the  time 
occupied  in  reading,  these  strains  are  not  present.  One  for- 
gets one's  self  and  the  passage  of  time  in  the  interesting 
event.  For  longer  times  the  filling  seems  to  have  a  markedly 
different  effect  according  as  the  time  is  regarded  as  it  is  being 
hved  through,  or  as  it  is  viewed  in  retrospect.  While  pass- 
ing, time  in  which  one  is  occupied  fully  and  during  which 
much  of  importance  is  happening  seems  short,  but  when 
viewed  in  retrospect  it  seems  long.  Empty  time,  on  the 
other  hand,  seems  long  in  the  passing  but  short  in  retrospect. 
During  convalescence  from  a  long  illness  the  days  drag 
interminably,  but  later  the  period  seems  inappreciable. 

Theories  of  Time  Perception.  —  Attempts  at  a  theory 
must  take  all  of  these  facts  into  consideration  and  we  must 
distinguish  three  ways  of  appreciating  time.  The  first 
applies  to  the  very  short  intervals,  those  under  600-7000-, 
below  the  indifference  period.  These,  it  has  been  suggested, 
are  appreciated  in  terms  of  rhythm,  since  under  that  limit 
stimuli  may  be  easily  grouped  into  rhythmic  wholes.  The 
intervals  are  too  short  to  be  appreciated  for  themselves, 
they  cannot  be  attended  to,  and  so  do  not  reach  their  full 
development.  The  second  is  effective  for  times  between 
600  or  700  (X  and  two  to  four  seconds;  this  is  real  time.  It 
is  apparently  appreciated  in  terms  of  internal  experiences, 
expectation  processes,  and  other  more  definitely  kinassthetic 
sensations.  The  length  of  the  time  is  estimated  in  terms 
of  the  intensity  of  the  strains.  Short  times  give  strains  no 
chance  to  become  strong,  but  their  strength  grows  with  the 
longer  times.  Strains  of  the  muscles  that  accompany  atten- 
tion, strains  of  expectation,  even  strains  that  come  with 


PERCEPTION  OF  TIME  355 

respiration  or  with  holding  the  breath,  have  been  asserted 
to  form  the  basis  of  the  appreciation  of  the  passage  of  time. 
The  influence  of  the  strength  of  the  limiting  stimuH  would 
suggest  the  importance  of  the  strains  of  attention  in  the 
estimation  of  time,  as  would  the  eflfect  of  the  content  of  time. 
When  the  interval  is  empty,  attention  is  more  fully  attracted 
to  the  passage  of  time,  the  strains  are  more  pronounced, 
and  the  time  seems  longer.  In  the  same  way  with  longer 
intervals  when  there  is  nothing  to  do,  the  strains  of  expec- 
tation occupy  consciousness  and  time  seems  long,  while, 
when  one  is  busy,  attention  is  otherwise  occupied  and  there 
is  constant  change,  constant  relaxation,  the  strains  never 
rise  to  great  intensities,  and  in  consequence  one  is  not  im- 
pressed with  the  fact  that  time  is  passing. 

Times  longer  than  from  two  to  four  seconds  are  appar- 
ently not  directly  experienced  in  the  passing,  but  are  only 
experienced  as  past.  They  fall  outside  of  the  present,  are 
constituted  for  the  most  part  by  memories  of  past  events 
revived  in  the  present.  They  are  estimated  in  terms  of 
events  that  have  happened  in  them,  in  terms  of  the  occur- 
rences which  fill  them.  In  this  they  differ  altogether  from 
the  shorter  intervals  that  may  be  directly  appreciated,  and 
in  consequence  show  the  reverse  illusions.  Thus,  times  that 
are  filled  with  interesting  events  seem  long  when  they  are 
looked  back  upon,  although  they  seem  short  in  passing; 
while  times  in  which  nothing  happens  seem  short  in  retro- 
spect, although  extremely  long  in  their  passage.  It  is  this 
that  explains  the  seeming  decrease  in  the  length  of  the  days 
and  weeks  with  advancing  years.  When  one  is  young,  all 
is  interesting  from  its  newness,  and  is  always  attended  to; 
as  time  goes  on,  nearly  everything  becomes  familiar,  and 
receives  less  and  less  attention,  and  so  less  and  less  is  remem- 
bered in  retrospect.     In  general,  times  depend  upon  an 


356        FUNDAMENTALS   OF  PSYCHOLOGY 

appreciation  of  that  which  fills  them.  Very  short  times  are 
apparently  known  from  rhythm,  longer  times  from  the 
physiological  processes,  contractions  and  what  not,  that 
give  the  feeling  of  expectation  and  strain;  while  intervals 
longer  than  from  two  to  four  seconds,  are  appreciated 
from  the  events  that  happen  in  them. 

REFERENCES 

Ladd-Woodworth:  Physiological  Psychology,  Chs.  II,  IV- V. 
Myers:  Experimental  Psychology,  Chs.  XX-XXIII. 
Titchener:  Textbook,  pp.  303-373. 
James:  Principles,  Vol.  I,  Ch.  XV. 
Benussi:  Psychologic  der  Zeitauffassung. 

The  General  Laws  of  Perception 

While  space  and  time  may  be  treated  separately,  since 
practically  all  perceptions  imply  them  and  they  are  con- 
sidered to  have  an  existence  independent  of  the  objects 
found  in  them,  certain  laws  of  perception  can  be  illustrated 
only  by  a  study  of  the  way  in  which  separate  objects  are 
perceived.  Speaking  generally,  it  may  be  said  that  a  per- 
cept is  practically  never  merely  a  mass  of  bare  sensations. 
The  sensations  at.  most  provide  a  suggestion  which  is  devel- 
oped in  consciousness  to  make  the  object  as  we  appreciate 
it.  In  optical  illusions,  certain  elements  are  added,  certain 
others  are  subtracted  from  the  immediate  group  of  sensa- 
tions, before  we  have  the  final  percept.  One  is  not  aware 
of  either  the  additions  or  the  subtractions,  much  less  of  the 
sensations  as  immediately  given  before  the  modifications 
are  made.  This  same  process  may  be  demonstrated  to 
take  place  in  practically  every  perception  as  we  appreciate 
the  nature  of  the  real  object.  We  are  aware  only  of  the 
final  process,  the  object,  but  we  can  be  sure  from  experi- 


READING  AS   PERCEPTION  357 

mental  data  that  this  is  not  merely  a  mass  of  sensations, 
but  is  the  result  of  a  complicated  series  of  mental  operations. 

Reading.  —  One  of  the  best  means  of  studying  the 
various  laws  of  perception  is  furnished  by  reading.  Here 
the  material  is  relatively  simple  and  we  have  fairly  full 
experimental  evidence  concerning  the  different  phases  of 
the  process.  First  it  may  be  asserted  that  the  word,  not 
the  letter,  is  the  unit  for  reading  This  is  demonstrated 
by  the  experiment  on  the  distribution  of  attention.  As 
was  said  in  connection  with  attention,  five  or  six  letters  is 
the  maximum  that  can  be  distinguished  on  short  exposure, 
but,  when  combined  into  words,  twenty-five  to  thirty  letters 
may  be  read  at  a  single  exposure  of  t^o  second.  Evidently 
something  must  be  added  to  what  is  seen,  or  the  word  must 
be  read  as  a  whole  rather  than  by  single  letters.  There  is 
evidence  that  both  processes  go  on  in  some  degree.  Zeitler 
and  the  writer  found  that  the  reader  was  influenced  by  the 
general  form  of  the  word  as  determined  by  the  relative 
positions  of  high  and  low  letters,  the  length  of  the  letters, 
etc.  This  is  indicated  again  in  print  by  the  fact  that  one  is 
much  more  likely  to  make  mistakes  and  to  have  greater 
difficulty  in  making  out  the  words  if  the  upper  parts  of  the 
words  are  cut  off  than  if  the  lower  be  covered. 

On  the  other  hand,  the  proofreader's  illusion  indicates 
that  there  is  a  constant  tendency  to  supply  letters  or  parts 
of  letters  from  memory,  to  add  centrally  to  peripherally 
aroused  sensations.  The  writer  found  that  if  words  were 
printed  with  letters  omitted,  with  blurred  letters,  or  with 
substitutions,  and  shown  for  a  fifth  of  a  second  or  less, 
they  were  read  in  a  large  proportion  of  the  cases  as  if  per- 
fect. The  readers  would  occasionally  give  reports  of  the 
character  of  the  letters,  supplied  or  transformed,  which 
indicated  that  they  belonged  in  the  class  of  the  centrally 


358        FUNDAMENTALS   OF  PSYCHOLOGY 

aroused  sensations.  The  letters  that  were  supplied  or 
replaced  were  faint,  had  a  pecuHar  color,  or  seemed  to  be 
less  permanent  than  the  others.  The  Hkehhood  of  reading 
the  misprinted  word  as  if  it  were  correctly  printed  was  much 
increased  if  a  word  associated  with  the  word  to  be  shown 
was  called  before  the  exposure.  This  gave  the  right  atti- 
tude or  setting  for  seeing  the  word  intended.  That  supple- 
menting is  a  factor  even  in  the  simplest  reading  is  shown 
by  the  large  number  of  misprints  that  are  overlooked,  some 
even  by  the  most  accurate  proofreaders.  The  supplements 
in  this  case  are  not  so  permanent  as  are  those  in  optical 
illusions.  The  latter  persist  for  a  considerable  time  in 
spite  of  all  that  one  can  do,  and  can  be  destroyed  only  by 
a  long  period  of  practice,  but  the  proofreader's  illusion 
vanishes  when  first  one  looks  to  make  sure  that  a  mistake 
has  not  been  made. 

Reading  Pauses.  —  One  might  deny  that  the  conditions 
of  ordinary  reading,  in  which  all  the  time  that  may  be  de- 
sired is  given  for  looking,  are  similar  to  those  in  which  the 
exposure  is  Hmited  to  a  period  too  short  to  permit  eye 
movements  or  wandering  of  attention.  Recent  studies  of 
the  mechanism  of  reading  show,  however,  that  the  con- 
ditions are  not  markedly  different.  In  the  first  place  it 
has  been  found  that,  while  reading,  the  eyes  do  not  move 
steadily  along  the  Une  with  full  time  for  t"he  observation 
of  all  details,  but  make  a  few  brief  pauses.  Photographs 
of  the  eyes  as  they  move  along  the  line  show  that  they  stop 
only  from  three  to  six  times  in  a  Hne  of  ordinary  length, 
and  then  for  but  a  very  short  time,  approximately  a  fifth 
of  a  second.  The  number  of  stops  varies  greatly  with  the 
character  of  the  material  to  be  read.  In  reading  a  novel 
or  similar  light  Kterature,  the  number  is  a  minimum,  and 
rises  to  a  maximum  with  difficult  material,  in  proofreading, 


READING  AS   PERCEPTION  359 

and  for  children  who  are  learning  to  read.  One  really 
takes  a  series  of  snap  shots  of  a  line  and  pieces  it  together 
from  them,  rather  than  reading  continuously.  There  can 
be  apparently  no  reading  while  the  eyes  are  in  motion; 
they  move  so  rapidly  that  nothing  but  a  blur  of  after-images 
is  left  on  fhe  retina,  and  as  this  gives  no  knowledge,  we  have 
learned  to  pay  no  attention  to  it. 

Reading  a  Process  of  Supplementation.  —  All  this  leads 
to  the  conclusion  that  ordinary  reading  is  a  process  of  in- 
ferring unconsciously  from  the  form  of  the  words  and  a 
few  letters  what  the  word  actually  is.  This  process  of  in- 
ference is  really  nothing  more  than  associating  with  the 
letters  seen  certain  other  letters  frequently  found  with  them, 
or  of  associating  whole  words  with  what  little  of  the  word  is 
seen.  Like  all  associations,  these  are  under  the  control 
of  the  mental  attitude,  largely  determined  by  the  context 
and  the  knowledge  that  the  reader  can  bring  to  the  reading. 
The  influence  of  the  context  can  be  seen  in  the  different 
pronunciation  and  interpretation  of  a  word  composed  of  the 
same  letters  in  different  contexts.  '  Lead'  has  one  pronun- 
ciation when  the  subject  of  the  sentence,  another  when 
it  is  the  predicate,  and  we  do  not  think  of  the  one  when 
the  other  is  meant.  The  meaning  is  determined  by 
the  context,  and  what  has  gone  before.  Still  more  striking 
is  the  difference  in  pronunciation  and  interpretation  that 
attaches  to  the  same  group  of  letters  in  different  languages. 
Man  has  an  entirely  different  sound  and  meaning  in 
English  and  in  German,  and  many  other  illustrations  could 
be  found.  Sufiice  it  to  say  that  the  sounds  or  ideas  that 
are  aroused  depend  very  definitely  upon  the  context. 

In  reading  it  is  evident,  too,  that  the  process  of  per- 
ceiving or  of  interpreting  is  not  complete  when  the  word 
as  such  has  been  seen.    The  process  of  translation  into 


36o        FUNDAMENTALS   OF  PSYCHOLOGY 

ideas  follows.  Sometimes  one  sees  the  words  and  follows 
them  along  with  the  sound  of  the  spoken  word,  and  thus  has 
the  ideas  produced,  indirectly.  Experiments  show  that  to 
depend  upon  translation  through  internal  speech  is  of  no 
advantage  and  makes  reading  unnecessarily  slow.  More 
frequent  in  the  adult  is  the  immediate  translation  of  the 
words  as  seen  into  images  or  ideas  of  some  sort.  As  one 
reads  in  the  most  complete  way,  pictures  or  more  abstract 
ideas  accompany  the  reading.  The  clearer  the  style, 
the  more  immediately  do  the  ideas  follow  upon  the  percep- 
tion of  the  words  and  the  less  prominent  are  the  words, 
until  with  a  maximum  of  clearness  the  words  are  largely 
neglected  and  the  meaning  alone  comes  to  consciousness. 
This  meaning  may  take  the  form  of  picturing  the  scenes 
described,  of  merely  appreciating  the  abstract  meaning, 
or  of  something  intermediate.  In  any  case,  the  outUnes  of 
black  and  white  that  constitute  the  words  start  the  associa- 
tion processes  that  lead  to  the  ideas,  and  these  associates 
are  controlled  by  the  wider  setting  and  wider  knowledge 
of  the  individual  at  the  moment.  The  process  is  much 
like  that  in  ordinary  recall  except  that  the  stimuli  are  con- 
stantly received  from  the  words.  The  revival  of  the  earher 
experiences  is  controlled  by  the  laws  of  association  and  by 
the  context  in  a  degree  that  practically  amounts  in  many 
cases  to  new  construction. 

Understanding  Spoken  Language.  —  A  similar  process 
occurs  in  Hstening  to  another's  speech.  One  does  not 
appreciate  how  small  is  the  proportion  of  a  conversation 
that  is  heard  distinctly  until  one  attempts  to  follow  a  foreign 
language.  Then  it  is  seen  that  what  must  be  perfectly 
clear  to  a  native  as  a  vehicle  for  ideas  is  really  only  a  series 
of  grunts  and  hisses  with  an  occasional  word  clearly  enun- 
ciated.    Suggested  by  these,  the  words  or  the  ideas  are 


GENERAL  LAWS  OF  PERCEPTION         361 

supplied  through  association.  Bagley  has  shown  that 
there  is  a  process  of  filling  out  the  imperfections  of  sounds 
similar  to  the  interpretation  of  letters  in  reading.  The 
laws  of  supplementing  are  practically  the  same  in  the  two 
cases.  Something  is  given  by  the  ear,  this  suggests  words 
as  one  would  speak  them  one's  self  or  as  they  would  look 
on  the  printed  page.  This  is  all  that  is  really  appreciated, 
and  even  when  one  Hstens  for  the  words,  the  imperfections 
are  not  noticed.  When  one  hears  a  strange  accent,  the 
different  deviations  from  the  sounds  one  is  accustomed  to 
are  overlooked,  the  man  is  assigned  to  his  region  of  the 
country,  and  then  no  more  attention  is  paid  to  the  speech 
characteristics,  unless  one  be  interested  in  phonetics  or 
have  some  other  purpose  in  hearing  the  sounds,  and  in  such 
cases  the  sense  of  what  is  being  said  is  very  Hkely  to  be 
lost.  Artificial  languages  gradually  take  on  the  same  char- 
acter. The  separate  elements  become  united  into  word 
units,  and  then  acquire  meaning,  as  do  words  themselves. 
This  comes  out  particularly  clearly  in  learning  the  tele- 
graphic language.  There  at  first  the  sounds  are  heard  as 
small  groups  and  put  together  painstakingly  and  slowly 
into  letters,  but  gradually  words  are  heard  as  wholes  and 
the  meaning  is  suggested  by  a  few  words  and  omissions 
are  filled  in  as  in  ordinary  speech.  Supplementing  follows 
the  same  laws  as  in  reading  or  listening. 

Resume  of  the  General  Laws  of  Perception.  —  If  one 
may  extend  and  generaHze  the  laws  of  perception  in  read- 
ing and  Hstening,  it  may  be  said  that  perception  is  primarily 
a  process  of  arousing  old  experiences  through  association. 
These  associations  are  controlled  by  both  the  subjective 
and  the  objective  factors.  Some  few  sensations  always 
serve  as  the  incentive  to  the  perception  process,  but  they 
serve  as  the  incentive  only.     By  them  associations  are 


362        FUNDAMENTALS  OF  PSYCHOLOGY 

aroused  and,  in  that  arousal  all  the  experiences  that  have 
had  any  bearing  on  the  process  contribute  their  share. 
Some  of  the  associations  are  determined  through  mere 
frequency  of  appearance  with  the  original  stimulus;  others 
depend  upon  the  attitude  in  which  one  is  at  the  moment  of 
looking  or  listening,  and  upon  the  inherent  probabilities 
of  the  situation.  That  one  is  not  more  often  misled  is  due 
to  the  fact  that  objective  situations  repeat  themselves  so 
frequently,  quite  as  frequently  as  do  ideas.  It  is  safe  on 
the  whole  to  assume  that  what  we  take  as  the  sign  of  an 
old  situation  really  accompanies  that  situation,  for  in  the 
vast  majority  of  cases  the  remainder  of  the  elements  are 
actually  present.  In  practice  it  would  take  more  trouble 
to  stop  to  investigate  than  to  take  the  chance  and  be  wrong 
the  few  times  that  the  new  does  not  correspond  to  the  old. 
It  is  striking,  however,  that  in  this  case  alone  one  does  not 
distinguish  between  real  sensations  and  the  recalled  images. 
Centrally  and  peripherally  aroused  sensations  are  combined 
in  almost  all  perceptions,  but  one  never  can  tell  where 
the  sensations  stop  and  mental  supplements  begin.  One 
seems  as  real  as  the  other. 

The  Influence  of  the  Type  in  Perception.  —  In  conclu- 
sion we  may  again  emphasize  the  importance  of  type  or 
concept  in  perception.  This  is  a  factor  common  to  both 
perception  and  reasoning,  —  this  is  the  tendency  to  replace 
a  particular  phase  or  aspect  of  an  object  by  what  has 
proved  to  be  its  more  general  or  universal  form.  Usually 
one  sees  things  as  the  previous  experience  convinces  one 
they  must  be,  rather  than  as  they  appear  at  the  particular 
moment.  Thus,  one  usually  does  not  notice  shadows  as 
shadows,  although  they  may  aid  much  in  the  interpreta- 
tion of  the  form  of  the  surface  on  which  they  fall.  Simi- 
larly, one  does  not  notice  how  indistinct  are  objects  in  the 


GENERAL  LAWS   OF   PERCEPTION        363 

field  of  vision  a  little  distance  from  the  fixation  point. 
What  is  seen  is  at  once  translated  into  an  object  of  perfect 
form  with  full  detail  and  distinctness,  and  all  else  serves  as 
a  mere  background.  Still  more  striking  is  the  correction 
of  the  size  of  various  objects.  The  standard  size  varies  for 
the  different  objects.  No  matter  how  small  or  how  large 
the  image  may  be  under  a  given  set  of  circumstances,  it  is 
increased  or  decreased  to  a  standard  size.  The  image  it- 
self is  never  seen,  the  fact  that  it  has  been  changed  in  its 
size  also  is  not  noticed;  the  corrected  standardized  impres- 
sion at  once  replaces  the  retinal  image.  This  standard  we 
regard  as  the  real  object. 

Similar  tendencies  to  replace  mere  sensation  groups  by 
concepts  or  by  standardized  objects  may  be  seen  any- 
where. The  neglect  of  after-images,  of  contrast  colors,  the 
overlooking  of  imperfections  in  the  media  of  the  eye  that 
can  be  seen  clearly  when  one  looks  for  them  in  a  lamp 
flame,  overlooking  the  retinal  blood  vessels  in  the  visual 
field,  —  all  of  these  omissions  are  quite  as  apparent  as  is 
the  addition  of  quahties  or  characteristics  not  given  in  sen- 
sation. Equally  striking  are  the  changes  in  the  forms  of 
objects  seen  in  perspective.  As  any  article  of  furniture  is 
looked  at,  the  square  corners  are  either  increased  to  obKque 
angles  or  reduced  to  acute  angles,  according  to  the  side 
from  which  one  looks.  A  hundred  students  looking  from 
different  directions  at  the  lecturer's  reading  desk  will  each 
receive  a  different  impression,  different  in  shape  as  well  as 
in  size,  but  the  object  is  the  same  for  all.  The  perception 
is  changed  in  being  seen,  or  a  standard  object  is  made  to 
replace  the  various  images,  so  that  the  final  result  is  the 
same  for  each  observer.  This  process  of  replacing  the  crude 
image  by  a  standard  object,  an  object  that  has  been  devel- 
oped by  all  of  the  individual's  experiences,  that  has  been 


364        FUNDAMENTALS   OF  PSYCHOLOGY 

gradually  corrected  by  being  seen  under  different  condi- 
tions, by  being  handled,  and  even  by  making  similar  ob- 
jects or  seeing  them  made,  is  practically  universal.  It  is 
the  developed  standard  object  that  always  comes  to  con- 
sciousness, just  as  it  is  the  corrected  standard  space  that  is 
always  used  as  the  basis  of  reference.  To  anticipate  the 
discussion  of  a  later  problem,  it  may  be  said  that  we  per- 
ceive concepts  rather  than  sensations.  As  concepts  that 
have  developed  in  this  way,  we  have  not  merely  objects, 
but  space  and  time  and  ssmilar  abstractions  which  are  in 
part  components  of  the  objects,  in  part  to  be  regarded  as 
independent. 

REFERENCES 

Huey:  Psychology  of  Reading. 
Erdmann  and  Dodge:  Ueber  das  Lesen. 
Gray:  Individual  Differences  in  Reading  Ability. 
Pillsbury:  The  Role  of  the  Type  in  Simple  Mental  Processes. 
Philosophical  Review,  Vol.  XX,  pp.  498  ff. 


CHAPTER  XII 
MEMORY 

Memory  is  a  topic  that  bulks  very  large  in  the  discus- 
sions of  daily  life.  In  the  complete  form  it  may  be  defined 
as  the  recurrence  of  a  group  of  experiences  with  knowledge 
of  the  time  and  the  place  in  which  they  were  experienced 
before.  Memory  is  related  to  centrally  aroused  sensation 
in  very  much  the  same  way  that  perception  is  related  to 
sensation.  It  is  a  group  of  centrally  excited  sensations  ac- 
cepted as  representing  some  earlier  seen  object  or  previous 
event,  as  perception  represents  an  object  actually  present. 

While  the  fundamentals  of  memory  have  been  discussed, 
there  is  much  of  more  particular  application  that  remains 
to  be  considered  —  questions  as  to  how  the  association 
processes  may  be  used  to  the  best  advantage  in  the  accu- 
mulation and  application  of  knowledge.  We  may  con- 
veniently divide  memory  into  four  part  processes,  —  learn- 
ing, retention,  recall,  and  recognition.  Learning  is  no  more 
than  the  formation  of  association;  retention  is  the  persist- 
ence of  those  associations;  recall  is  the  rearousal  of  old  ex- 
perience; and  recognition,  the  process  of  assigning  the 
events  to  the  time  of  their  first  appearance.  Although  as- 
sociation has  been  treated  in  general,  we  must  consider 
here  a  large  number  of  special  rules  and  laws  developed 
through  experiment  that  throw  new  light  on  the  nature 
and  use  of  memory.  To  have  the  associations  is  not  iden- 
tical with  being  able  to  use  them.  We  shall  weave  to- 
gether the  results  obtained  from  experiments  on  the  first 
365 


366        FUNDAMENTALS   OF  PSYCHOLOGY 

three  processes,  before  we  consider  recognition  which  in- 
volves certain  relatively  new  principles. 

We  may  distinguish  in  the  discussion  of  memory  between 
the  retention  and  recall  of  concrete  objects  and  the  recall 
of  words  or  symbols.  The  process  is  different  in  the  two 
cases  because  the  symbols  must  be  remembered  directly, 
while  the  concrete  objects  are  sometimes  remembered  di- 
rectly and  sometimes  translated  into  symbols  which  repre- 
sent them.  The  differences  are  sufficient  to  make  it  desir- 
able to  treat  the  operations  separately.  The  first  we  may 
call  observational,  the  second,  verbal  memory. 

Memory  of  Objects  and  Events 

Observational  Memory.  —  Observational  memory  de- 
rives its  great  practical  importance  from  the  fact  that  the 
evidence  of  the  witness  on  the  stand  must  depend  for  its 
accuracy  upon  this  type.  It  is,  of  course,  also  the  method 
that  we  use  in  describing  the  events  of  the  day  in  conver- 
sation. Much,  too,  of  the  work  of  the  observational  sci- 
ences that  is  not  recorded  at  once  in  notes  depends  upon 
the  accuracy  of  this  form  of  memory.  We  may  say  that 
the  accuracy  of  recall  depends:  first,  upon  the  way  the 
material  is  seen  at  the  time  of  the  observation;  secondly, 
upon  the  time  that  elapses  between  observation  and  re- 
port; and  thirdly,  upon  the  circumstances' effective  at  the 
time  of  recall.  What  is  seen  depends  upon  the  way  the  ob- 
server attends  and  upon  the  way  he  translates  what  he 
sees  into  words  for  retention  and  recall.  Most  individuals 
will  notice  objects,  their  form,  position,  and  number  first, 
and  with  an  accuracy  diminishing  in  that  order.  Colors 
are  seldom  noticed.  Children  are  much  more  inaccurate 
than  adults  in  all  except  possibly  the  observation  of  colors. 
Special  practice  in  observation  of  any  kind  will  greatly  in- 


OBSERVATIONAL   MEMORY  367 

crease  the  accuracy  of  observation.  Practice  is  of  some 
general  value  in  calling  attention  to  what  is  Hkely  to  be 
overlooked,  and  enabling  the  observer  to  attend  especially 
to  that.  Accuracy  is  increased,  too,  by  describing  in  words 
what  is  seen,  and  remembering  the  words  rather  than  trust- 
ing to  the  images  alone.  Thus,  if  one  will  count  the  win- 
dows in  a  building  as  one  looks,  one  will  remember  the 
number,  but  if  one  attempts  to  count  them  in  the  memory 
picture,  the  result  is  very  hkely  to  be  wrong. 

Effect  of  Lapse  of  Time  on  Accuracy.  —  The  effect  of 
time  is  always  in  evidence.  Dallenbach  found  that  forget- 
ting took  place  rapidly  at  first  and  then  more  slowly,  a 
law  that  holds  for  forgetting  all  types  of  material.  Thus 
immediately  after  exposure,  ten  per  cent  errors  were  made; 
after  five  days  this  had  increased  to  fourteen  per  cent; 
after  fifteen  days,  to  eighteen;  and  after  forty-five  days  to 
twenty-two.  The  material  used  consisted  of  pictures,  and 
the  percentages  were  obtained  by  counting  the  number  of 
objects  in  the  picture  and  determining  what  per  cent  of 
them  was  recalled.  It  will  be  noticed  that  there  was  the 
same  increase  in  the  number  of  errors  between  one  day  and 
five  as  between  five  and  fifteen,  and  fifteen  and  forty-five. 

Most  errors  of  report  that  develop  at  the  moment  of  re- 
call are  due  to  the  suggestion  of  objects  that  were  not  actu- 
ally seen.  Any  idea  that  presents  itself  is  certain  to  sug- 
gest others,  and  this  suggestion  may  lead  the  observer  to 
think  that  it  was  actually  present.  This  is  an  extension  of 
the  tendency  for  what  is  present  to  suggest  at  the  moment 
of  observation  other  things  that  are  not  really  seen.  Some- 
thing is  definitely  recalled,  and  this  suggests  something 
else  that  usually  goes  with  it.  This  arousal  of  the  idea 
may  be  accepted  as  constituting  evidence  that  the  object 
was  really  seen.    Very  striking  is  the  influence  of  questions 


368        FUNDAMENTALS   OF  PSYCHOLOGY 

in  increasing  the  number  of  errors.  If  the  individual  is 
told  to  tell  all  that  he  saw,  he  will  make  a  report  that  is 
approximately  ninety  per  cent  correct.  If  he  is  questioned 
as  straightforwardly  as  possible  about  the  objects  in  the 
picture,  the  errors  will  increase  so  that  he  may  have  only 
seventy  per  cent  correct.  The  advantage  of  questioning, 
which  makes  it  essential  that  a  witness  be  questioned  in  a 
court,  is  that  many  things  he  might  report  on  will  not  sug- 
gest themselves  without  questions.  Experiments  show  that 
the  spontaneous  report  covers  only  twenty-five  to  forty  per 
cent  of  the  total  number  of  objects  present,  while  questions 
will  increase  this  range  to  fifty  or  sixty-five  per  cent.  What 
is  lost  in  accuracy  is  gained  in  range.  If  leading  questions 
are  asked,  particularly  if  they  assume  a  wrong  answer,  the 
percentage  of  errors  is  increased  much  more.  If  one  asks 
the  color  of  the  dog  in  the  background,  when  no  dog  was 
present,  about  half  of  the  individuals,  even  of  superior  in- 
telligence, will  give  some  color. 

Rote  Memory 

Experimental  Methods.  —  Careful  experiments  on  mem- 
ory were  first  made  by  Ebbinghaus  in  the  eighties  of  the 
last  century.  To  avoid  the  variation  in  degree  of  famihar- 
ity  and  interest  that  might  attach  to  words  or  any  other 
material  that  has  meaning,  nonsense  syllables  were  selected 
as  the  material  to  be  learned.  These  were  built  up  of  con- 
sonants and  vowels,  two  consonants  with  a  vowel  between. 
All  combinations  were  excluded  that  chanced  to  make 
sense.  Series  were  selected  by  lot  from  the  mass  of  sylla- 
bles. Ebbinghaus  wrote  his  series  upon  cards  and  then 
learned  them  by  shuffling  the  cards.  Most  later  workers 
have  arranged  the  syllables  upon  some  sort  of  revolving 
drum  that  exposes  them  at  regular  intervals  and  for  defi- 


OBSERVATIONAL   MEMORY  369 

nite  times.  They  are  said  through  regularly  as  they  are 
exposed,  until  they  can  be  repeated  once  or  twice  without 
mistake.  Ebbinghaus  measured  the  amount  of  effort  in 
learning  by  the  time  required,  but  most  later  writers  have 
chosen  the  number  of  repetitions  as  the  measure.  Two 
methods  have  been  used  to  test  the  accuracy  of  the  learn- 
ing or  the  amount  of  retention.  The  iirst,  known  as  the 
method  of  relearning,  was  used  by  Ebbinghaus.  It  con- 
sisted in  relearning  the  syllables,  and  assumed  that  the  dif- 
ference between  the  time  required  for  learning  and  for  re- 
learning was  a  measure  of  the  amount  retained.  This  also 
measured  the  value  of  the  method  of  learning  used.  In  a 
second  method,  the  method  of  paired  associates  developed 
by  Miiller  and  Schumann  and  extensively  used  since,  the 
syllables  are  learned  in  pairs  and  the  amount  retained  is 
measured  by  showing  the  first  member  of  each  pair  and 
asking  the  observer  to  supply  the  second.  The  percentage 
of  correct  answers  indicates  the  amount  retained.  In 
many  experiments,  the  time  required  for  speaking  the  sec- 
ond syllable  is  measured.  This  serves  as  an  indication  of 
the  strength  of  the  association  for  individual  pairs.  The 
shorter  the  interval  required,  the  stronger  is  the  associa- 
tion. Each  of  these  methods  has  given  valuable  results. 
They  frequently  supplement  each  other.  The  first  meas- 
ures primarily  the  effective  and  latent  memory  of  the 
whole;  while  the  second  permits  a  study  of  the  effective 
connections  between  members  of  the  pairs.  One  measures 
potential  habihty  to  recall;  the  other,  the  actual  recall. 

The  Laws  of  Learning 

Effect  of  Individual  Repetitions.  —  One  of  the  first  pre- 
liminaries to  the  application  of  the  method  was  to  deter- 
mine the  accuracy  of  the  method  itself.    This  involved  first 


370        FUNDAMENTALS  OF  PSYCHOLOGY 

a  determination  of  the  effects  produced  by  each  repetition 
when  a  number  of  repetitions  of  the  same  series  are  made. 
Ebbinghaus  tested  this  by  repeating  a  series  of  syllables 
eight  times  and  then  finding  the  time  required  to  relearn 
after  twenty-four  hours.  He  then  repeated  another  series 
sixteen  times  and  again  releamed  after  the  same  interval. 
These  experiments  were  repeated  up  to  sixty-four  repeti- 
tions of  a  series.    Within  these  hmits  the  amount  retained 


0  8  15  24  32  42  53  64 

Fig.  qi  .  —  Shows  the  increase  in  amount  retained  after  twenty-four  hours  with 
the  number  of  repetitions.  The  number  of  repetitions  is  plotted  on  the  horizontal, 
the  saving  in  seconds  on  the  vertical  axis. 

after  twenty-four  hours  was  directly  proportional  to  the 
number  of  original  repetitions.  The  last  repetitions  were  no 
less  effective  than  the  first  as  measured  by  the  amount  re- 
tained. The  diagram  shows  that  the  results,  when  plotted, 
lie  almost  in  a  straight  line.  Each  repetition  resulted 
in  a  saving  of  about  twelve  seconds  in  the  time  required 
for  relearning.  This  experiment  also  brings  out  the  fact 
that  learning  is  never  absolutely  complete  or  perfect.  Per- 
fect learning  at  the  moment  will  show  defects  in  a  few 


LAWS   OF  LEARNING  371 

hours  or  days,  and  the  duration  and  accuracy  of  retention 
may  be  increased  by  repetitions  much  beyond  the  number 
required  for  the  first  perfect  repetition.  Each  repetition 
will  have  the  same  effect  as  any  other  in  the  recall  of  the 
next  day  or  of  the  next  week. 

Relation  between  Length  of  Series  and  Number  of 
Repetitions.  —  One  of  the  more  striking  facts  in  connec- 
tion with  learning  is  the  great  increase  in  the  number  of 
repetitions  required  for  the  longer  series  as  compared  with 
the  shorter.  It  is  found  that  an  adult  can  remember  from 
6  to  8  syllables  or  11  to  13  numbers  with  a  single  repe 
tition,  while  Ebbinghaus  found  that  it  took  13  repetitions 
to  learn  a  series  of  10  syllables,  16.6  for  12,  30  for  16, 
44  for  24,  55  for  36.  As  the  number  of  syllables  in  a  se- 
ries increases,  the  number  of  repetitions  required  for 
learning  it  increases  much  more  rapidly  than  in  proportion 
to  the  increase  in  the  number  of  syllables.  The  most 
striking  increase  is  seen  when  the  series  is  just  longer  than 
can  be  learned  with  one  repetition.  The  number  of  sylla- 
bles that  may  be  learned  at  a  single  reading  to  be  repeated 
immediately  has  been  called  the  memory  span,  or  primary 
memory.  This  varies  very  markedly  with  age,  with  train- 
ing, and  with  the  individual.  It  may  be  much  increased 
by  training  at  any  age.  According  to  Meumann,  children 
from  seven  to  nine  can  usually  retain  no  more  than  two  or 
three  nonsense  syllables,  while  the  practised  adult  retains 
seven  or  eight. 

Effects  of  Grouping.  —  Learning  a  series  not  only  forms 
associations  between  the  contiguous  syllables  of  the  series, 
but  knits  the  whole  group  together  by  associations  formed 
between  all  of  the  syllables,  however  widely  they  may  be 
separated.  Ebbinghaus  demonstrated  this  by  learning 
certain  series  and  then  making  up  new  series  that  should 


372        FUNDAMENTALS   OF  PSYCHOLOGY 

consist  in  part  of  the  syllables  of  the  primary  ones.  Thus, 
he  would  select  syllables  that  had  been  separated  by  one 
syllable;  and  he  found  that  the  new  series  could  be  learned 
more  easily  than  new  syllables.  He  repeated  the  experi- 
ment, using  syllables  that  had  been  separated  by  two,  three, 
etc.,  syllables,  up  to  those  that  had  been  separated  in  the 
original  learning  by  as  many  as  eight.  He  found  in  each 
case  that  a  saving  could  be  shown  as  compared  with  entirely 
new  series.  The  results  prove  that  associations  are  formed 
between  the  remote  as  well  as  the  contiguous  elements  in 
a  series.  He  also  showed  that  associations  are  formed  in 
both  directions,  backward  as  well  as  forward.  Relearning 
a  series  backward  saves  about  one-third  of  the  time  which 
is  saved  in  relearning  forward.  It  has  also  been  shown  that 
some  connection  is  formed  between  the  syllable  and  its 
position  in  the  series.  Syllables  that  are  relearned  in  the 
same  absolute  position  in  a  series  are  relearned  more  easily 
than  when  they  take  a  new  position.  If  the  syllable  is  the 
third  or  the  seventh  in  the  series  and  is  kept  in  third  or 
seventh  place,  relearning  is  easier  than  if  it  is  shifted  to 
second  or  fifth  place  in  the  new  series.  All  of  these  bonds 
of  connection  aid  in  making  the  series  a  unit. 

Effects  of  Rhythm.  —  Anything  that  serves  to  unite  the 
syllables  into  minor  units  is  of  advantage  in  aiding  learning. 
One  of  the  means  employed  most  frequently  is  rhythm. 
In  repeating  a  series,  the  syllables  are  practically  always 
combined  in  rhythmic  units  and  given  an  accent.  Learning 
in  the  natural  rhythm  is  much  easier  than  in  a  forced 
rhythm  or  without  rhythm.  The  natural  rhythm  varies 
with  the  individual  and  probably  also  with  the  race,  but 
whatever  the  rhythm  used,  some  benefit  is  derived  from  it. 
The  rhythmic  unit  also  serves  as  a  subordinate  group 
within  which  associations  are  much  stronger  than  between 


LAWS  OF  LEARNING  373 

contiguous  syllables  of  different  groups.  Miiller  demon- 
strated this  by  first  learning  series  in  trochaic  rhythm 
and  then  forming  from  the  syllables  two  sets  of  new  sylla- 
bles. In  one  of  these,  the  syllables  were  relearned  in  the 
same  measures  as  in  the  original  series;  in  the  others,  the 
syllables  were  contiguous  but  had  belonged  to  different 
measures.  The  former  showed  a  saving  on  relearning  equiv- 
alent to  five  repetitions;  the  latter,  no  appreciable  saving. 
This  strong  association  within  the  group  holds,  not  merely 
for  the  grouping  in  rhythmic  units,  but  for  any  grouping. 
In  learning  nonsense  syllables,  practically  no  association  is 
formed  between  the  first  syllable  of  one  series  and  the  last 
of  the  preceding.  In  common  hfe  Httle  connection  is 
established  between  conversations  on  different  subjects 
with  different  persons,  even  if  one  immediately  succeeds 
the  other.  On  the  other  hand,  where  material  to  be  re- 
membered is  broken  up  into  smaller  groups  of  a  larger  series, 
members  of  these  groups  are  more  closely  associated  for 
themselves,  and  learning  the  groups  aids  in  learning  the 
total  series.  This  formation  of  subordinate  groups  is  of 
great  practical  importance,  and  we  shall  have  occasion  to 
refer  to  it  in  connection  with  the  development  of  meaning. 
Learning  by  Whole  and  Part.  —  One  of  the  most  im- 
portant practical  laws  for  learning  is  that  it  is  much  easier 
to  learn  any  selection  if  it  is  read  as  a  whole  instead  of 
being  learned  by  parts.  This  appHes  to  nonsense  material 
under  strict  experimental  conditions,  and  also  to  ordinary 
sense  material,  poems,  etc.  An  investigation  of  this  point 
was  first  undertaken  by  Miss  Steffens  under  the  direction 
of  Professor  Miiller.  It  consisted  in  comparing  the  time 
required  for  poems  when  learned  as  most  people  incHne  to 
learn  them,  a  line  or  a  couplet  at  a  time,  with  the  time 
required  when  they  are  read  through  from  beginning  to  end 


374        FUNDAMENTALS   OF  PSYCHOLOGY 

each  time.  The  results  indicate  that,  in  practically  every 
case,  learning  as  a  whole  is  more  economical  than  learning 
in  parts.  The  saving  amounted  to  about  ten  per  cent  in 
Miss  Steffens'  experiments  and  held  for  children  as  well  as 
for  adults.  Later  investigations  by  Meumann  showed  that 
two  stanzas  required  thirty-three  repetitions  by  the  part 
method,  and  only  fourteen  for  the  whole  procedure.  It 
should  be  said  that  unless  some  method  of  keeping  the 
repetitions  at  a  uniform  rate  be  employed,  the  learner  tends 
to  lose  interest  and  to  repeat  more  slowly  than  he  will  if 
he  is  permitted  to  learn  by  parts.  In  some  experiments 
this  loss  in  rate  almost  offset  the  advantage  gained  from  the 
need  for  fewer  repetitions.  With  much  practice,  this  loss 
may  be  overcome.  The  law  has  been  demonstrated 
repeatedly.  Not  only  does  learning  require  fewer  repeti- 
tions, but  the  material  learned  as  a  whole  is  much  better 
retained  than  material  learned  in  parts.  There  is  also  a 
fairly  wide  Hmit  of  appHcation,  as  the  whole  method  was 
found  more  economical  by  Pyle  for  selections  that  required 
as  much  as  fifty  minutes  to  read  through. 

The  reasons  for  the  greater  efficiency  are  threefold : 

1.  They  save  much  of  the  time  ordinarily  wasted 
in  needless  repetitions.  In  the  part  method,  the  first 
part  of  the  selection  is  repeated  more  times  than  neces- 
sary through  going  back  to  connect  the  later  learned 
with  the  earher.  There  are  several  times  as  many 
repetitions  of  the  first  as  of  the  later. 

2.  Needless  associations  are  made  each  time  the 
reader  goes  back  from  the  end  of  a  Hne  to  its  beginning. 
These  take  time  and  also  may  interfere  with  the  forma- 
tion of  the  correct  associates. 

3.  As  was  said  above,  the  connection  of  a  word  with 
its  position  in  the  selection  is  of  some  advantage  in 


LAWS   OF  LEARNING  375 

learning,  and  the  whole  method  always  retains  the 

absolute  position  of  each  word. 
Meumann  and  his  pupils  have  shown  that  certain  inter- 
mediate methods  may  improve  on  the  strict  method.  Thus, 
it  is  frequently  an  advantage,  after  a  number  of  repetitions 
of  the  whole,  to  repeat  several  times  the  parts  of  the  selec- 
tion that  offer  special  difficulties,  and  to  learn  them  without 
making  unnecessary  repetitions  of  the  easier  portions.  One 
can  also  obtain  some  of  the  advantages  of  the  part  method 
by  making  pauses  at  certain  places,  then  in  each  case 
going  on  from  that  place  after  a  few  seconds.  These  pauses 
seem  to  attract  particular  attention  to  the  words  preceding 
and  succeeding  them,  without  the  disadvantage  of  forming 
useless  connections.  In  general,  it  is  recommended  that 
one  read  through  the  selection  to  be  learned  a  few  times  as 
a  whole;  then,  as  fatigue  comes  on,  introduce  the  pauses 
and,  when  it  becomes  evident  that  certain  parts  are  offering 
special  difficulties,  make  an  extra  number  of  repetitions 
of  those  parts  until  they  are  learned,  then  add  a  few  repeti- 
tions of  the  whole  to  weld  all  together. 

Distributed  Repetitions  More  Effective.  —  Another  law 
that  is  equally  well  estabhshed,  quite  as  important  in  prac- 
tice, and  even  more  interesting, is  the  so-called  law  of  divided 
repetitions.  Briefly,  this  is  that  the  more  the  repetitions 
are  distributed  over  different  days,  the  fewer  the  repetitions 
required  and  the  more  thoroughly  the  material  is  mastered. 
This  conclusion  was  first  carefully  investigated  by  Jost. 
He  tried  learning  nonsense  syllables  with  twenty-four 
repetitions  at  one  time,  then  similar  series  with  eight 
repetitions  per  day  for  three  days,  then  four  for  six  days, 
and  finally  two  a  day  for  twelve  days.  It  was  found  when 
they  were  tested  by  the  method  of  paired  associates  twenty- 
four  hours  after  the  last  repetition,  that  the  fewer  the  repe- 


376        FUNDAMENTALS   OF  PSYCHOLOGY 

titions  each  day,  the  greater  was  the  amount  retained. 
Ebbinghaus  had  earlier  compared  greater  numbers  of  repe- 
titions. On  one  occasion  he  read  a  series  of  twelve  syllables 
68  times  and  found  that  twenty-four  hours  later  he  needed 
seven  repetitions  to  relearn.  Then  he  repeated  another  of 
the  same  length,  lyi,  12,  and  8i  times,  a  total  of  38,  and 
found  but  five  repetitions  were  needed  for  relearning  twenty- 
four  hours  later.  Still  later  Miss  Perkins  ^  continued  the 
extension  of  distributions,  comparing  accumulated  repeti- 
tions of  eight  a  day  for  two  days,  with  four  and  two  and  one 
repetition  per  day,  every  other  day,  every  third,  and  every 
fourth  day.  The  results  were  tested  after  fourteen  days 
and  proved  even  more  striking  than  those  of  the  earHer 
tests  which  were  made  after  twenty-four  hours.  Eight 
repetitions  a  day  for  two  days  gave  only  from  9  to  17  per 
cent  correct  responses,  and  the  larger  number  was  obtained 
when  three  days  were  permitted  to  elapse  between  each 
series  of  eight  repetitions.  Four  readings  a  day  gave  from 
25  to  41  per  cent,  with  larger  values  for  the  wider  distribu- 
tion of  repetitions;  two  a  day  gave  from  45  to  78  per  cent, 
while  a  single  repetition  every  day  gave  79  per  cent;  a 
single  repetition  every  other  day,  72  per  cent;  ever)^  third 
day,  82  per  cent,  and  every  fourth  day,  68  per  cent.  It 
would  seem,  then,  that  one  repetition  every  second  or  third 
day  gives  a  maximum  value  for  learning. 

This  law  has  been  tested  a  number  of  times  on  children 
and  adults,  and  even  on  the  learning  of  animals,  and  always 
with  the  same  results.  Ulrich^  found  that  white  rats  could 
learn  a  maze  with  fewest  repetitions  if  they  were  given  one 
trial  each  third  day.  It  holds  also  for  sense  material  as 
well  as  for  nonsense  syllables.     The  explanation  of  the 

^  Perkins,  British  Journal  of  Psychology,  Vol.  7,  p.  253. 
''Watson,  Behavior,  pp.  228  ff. 


LAWS   OF  LEARNING  377 

advantage  of  divided  repetitions  was  suggested  by  some  of 
the  experiments  of  Jost.  He  found  that,  when  he  compared 
the  number  of  repetitions  required  to  develop  completely 
two  sets  of  associates  of  equal  strength  but  of  different  ages, 
the  older  set  required  fewer  repetitions  than  the  newer. 
His  method  was  to  learn  one  series  of  syllables  twenty-four 
hours  before  and  then  to  make  a  few  repetitions  of  another 
series  a  few  hours  before  the  test.  The  amount  retained  was 
tested  by  the  method  of  paired  associates.  When  three 
times  as  many  correct  associates  could  be  given  from  the 
newer  series,  it  required  almost  the  same  number  of  repeti- 
tions to  bring  each  to  the  point  where  it  could  be  said 
through  without  mistake.  When  the  number  of  correct 
associates  that  could  be  given  was  approximately  the  same 
for  both  series,  the  older  series  could  be  fully  learned  much 
more  easily  than  the  more  recent.  His  theory  is  that  the 
associations  continue  to  grow  strong,  to  *  set,'  for  some 
time,  perhaps  for  two  or  three  days  after  they  are  first 
formed.  That  associations  tend  to  increase  in  strength 
for  a  few  days  is  known  as  'Jost's  Law.'  This  unearned 
increment  that  comes  from  the  setting  process  makes  it 
much  easier  to  bring  them  back  to  full  effectiveness  some 
time  after  the  learning,  than  if  no  time  is  permitted  to 
elapse  after  the  repetitions  are  first  made.  It  is  possible  to 
connect  this  setting  process  with  the  continued  activity, 
perseveration  tendency,  that  constitutes  the  primary 
memory  or  immediate  retention.  This  setting  is  one  more 
expression  of  the  inertia  of  the  nervous  system 

Several  important  practical  deductions  may  readily  be 
drawn  from  this  law.  Obviously,  it  connects  well  with 
the  preceding  law,  since,  if  one  is  to  read  through  each  time, 
only  short  selections  could  be  learned  in  any  one  day. 
Coupled  with  the  advantage  from  divided  repetitions,  it 


378        FUNDAMENTALS  OF  PSYCHOLOGY 

gains  full  force,  since,  if  the  selection  be  not  learned  at  the 
first  sitting,  it  is  an  advantage  to  wait  a  day  or  two  before 
proceeding  to  complete  the  learning.  Again  the  bearing 
upon  the  famiHar  topic  of  cramming  is  quite  evident.  What 
is  repeated  often  at  periods  considerable  distances  apart  is 
learned  thoroughly,  while  accumulated  repetitions  in  a  brief 
period  produce  shght  effect  and  one  that  quickly  disappears. 
This  is  more  certain  from  the  fact  that  divided  repetitions 
leave  much  more  persistent  effects  than  accumulated.  In 
general,  the  more  the  repetitions  are  divided,  up  to  one 
every  third  day,  the  more  permanent  will  be  the  learn- 
ing. 

Rate  of  Repetitions.  —  Other  factors  that  affect  learning 
are  the  rate  at  which  the  material  is  read  and  the  degree 
of  activity  or  the  degree  of  attention  given  it.  The  rate  of 
repetition  has  been  several  times  investigated  with  sHghtly 
different  results.  Ebbinghaus  first  asserted  that  the  more 
rapid  the  rate,  the  quicker  the  learning.  Ogden  modified 
this  by  showing  that  learning  was  quickest  when  reading 
was  at  the  fastest  rate  possible  without  too  much  effort. 
Part  of  this  difference  lay  in  the  fact  that  Ebbinghaus  used 
the  time  alone  as  a  measure  of  effectiveness;  Ogden  em- 
ployed both  time  and  the  number  of  repetitions.  Meu- 
mann,  as  a  result  of  experience  gained  from  many  investiga- 
tions, concludes  that  the  best  rate  varies  with  the  individ- 
ual, the  material  to  be  learned,  and  the  familiarity  of  the 
learner  with  the  material.  It  is  best  to  read  relatively 
slowly  at  first  when  the  subject  matter  is  being  understood, 
and  more  rapidly  later,  up  to  the  point  where  the  effort 
begins  to  distract. 

Active  Repetitions  More  Effective  than  Passive.  —  The 
effects  of  the  attention  of  the  reader  have  been  investigated 
numerically  only  in  one  respect,  the  advantages  of  passive 


LAWS   OF  LEARNING  379 

reading  as  compared  with  active  repetition.  Witasek 
made  experiments  to  determine  the  best  combination  of 
reading  with  attempts  to  repeat.  He  found  that  the  most 
satisfactory  result  was  obtained  when  he  read  five  times 
and  then  repeated  fifteen  times  from  memory.  Skaggs  ^ 
found  it  an  advantage  to  intersperse  a  recitation  between 
each  reading  rather  than  to  have  more  than  one  of  each  in 
succession.  It  is  evident  that  attempting  to  repeat  from 
memory  requires  more  effort  and  will  hold  attention  much 
more  than  passive  reading.  It  should  be  said,  however, 
that  repeating  material  that  has  lost  its  freshness  in  an 
abstracted  state,  practically  without  attention,  will  give 
rise  to  learning  in  a  much  shorter  time  than  one  would 
think,  although  it  is  of  course  not  so  effective  as  repetition 
with  full  attention.  Still  another  factor  that  plays  an 
important  part  in  learning  is  the  intention  to  recall.  Meu- 
mann  and  others  found  a  saving  of  50  per  cent  or  more  if 
series  were  repeated  with  the  expectation  of  being  tested 
on  them  later,  as  compared  with  similar  series  that  were 
learned  without  knowing  that  the  learning  was  to  be 
tested.  Sanford^  found  almost  no  learning  to  result  from 
the  daily  reading  of  the  morning  service,  without  intention 
of  recall. 

Associative  Inhibition.  —  An  important  factor  in  pre- 
venting learning  is  the  presence  of  other  earlier  formed 
associations  with  the  syllables  to  be  learned.  Miiller  and 
Schumann  found  that,  if  two  associates  are  made  with  the 
same  syllable,  they  interfere  with  each  other,  and  the 
second  will  be  learned  with  greater  difficulty.  They 
demonstrated  this  by  learning  a  series  of  syllables  a,  d,  g, 

1  Skaggs,  Journal  of  Experimental  Psychology,  Vol.  3,  p.  424.    Cf.  Gates: 
Recitation  as  a  Factor  in  Memorizing.   Archives  of  Psy.,  No.  40. 
^  Studies  in  Experimental  Psychology.     Titchener  Volume,  p.  5. 


38o        FUNDAMENTALS   OF  PSYCHOLOGY 

etc.,  first  with  h,  e,  h,  etc.,  and  then  later  a  with  c,  d  with/,  g 
with  J,  etc.  It  was  found  that  it  took  considerably  longer 
to  learn  the  series  of  syllables  when  other  syllables  had 
already  been  connected  with  them  than  when  learned  for 
the  first  time.  In  the  experiments,  the  syllables  to  be  re- 
learned  were  interspersed  irregularly,  so  that  the  association 
with  the  old  positions  and  with  syllables,  that  were  near 
but  not  contiguous  in  the  first  connections,  should  not  aid 
in  the  relearning.  In  practical  Ufe  this  means  that  when 
one  thing  has  been  learned  with  another,  it  will  require 
a  longer  time  to  learn  it  with  a  second  than  if  it  had  not 
been  learned  with  the  first.  If  a  mistake  has  been  made, 
it  will  take  longer  to  correct  it  than  it  would  to  have  learned 
it  correctly  in  the  first  place.  But  where  several  things  are 
to  be  learned  in  the  same  connection,  it  is  found  that 
inhibition  ceases  to  be  effective  if  the  first  is  thoroughly 
learned  before  the  second  is  begun.  In  fact,  in  that  case 
there  is  apparently  some  saving,  since  the  familiarity  with 
the  old  saves  some  work  in  learning  the  new.  This  inter- 
ference of  earlier  formed  associates  with  the  formation  of 
new  ones  is  known  as  '  associative  inhibition.' 


Retention  and  Forgetting 

The  Rate  of  Forgetting.  —  The  investigations  of  the  re- 
tention of  associations  bear  largely  upon  the  rate  of  the 
disappearance  of  associations  with  time.  There  is  a  gen- 
eral tendency  toward  the  unlocking  of  associations  that 
begins  at  the  moment  of  reading  or  a  few  moments  later, 
and  goes  on  indefinitely.  Two  long  studies  have  been 
made  of  this  topic,  one  by  Ebbinghaus,  the  other  by 
Radossawljewitsch.  Their  results  may  be  compared  in 
the  table  on  the  following  page. 


LAWS   OF  FORGETTING 


381 


Per  Cent  Forgotten 

E 

R 

5  mm 

20  min 

I  hr 

8  hr.  45  min 

8hr 

1  day 

2  days      

6  days      

30  days      

120  days      

41.8 
55-8 
64.2 

66.3 

72.2 
74.6 
78.9 

2-5 

ir.4 
29-3 

52.6 
32.2 
39-1 
50-7 
79-8 
97.2 

The  main  difference  is  to  be  seen  in  the  fact  that  Ebbing- 
haus  found  a  larger  percentage  forgotten  in  the  shorter 
periods.     Both  indicate  a  relatively  rapid  forgetting  at 


24 


48 


144 


Fig.  92.  — Analysis  of  the  curve  of  forgetting  to  show  possible  cooperation  of 
perseveration  and  association.  The  full  line  shows  the  course  of  forgetting  after 
Ebbinghaus,  the  dotted  line  the  conjectured  decrease  in  the  primary  memory  (per- 
severation) and  the  dashes  the  initial  increase  in  the  strength  of  association  due  to 
perseveration. 

first,  and  a  relatively  slow  rate  in  the  longer  intervals. 
It  should  be  remembered  that  nonsense  syllables  were 
used  and  that  these  are  forgotten  much  more  quickly  than 
sense  material.     Sense  material  shows  a  somewhat  similar 


382        FUNDAMENTALS  OF  PSYCHOLOGY 

curve  but  a  much  slower  rate.  The  comparative  rapidity 
of  forgetting  during  the  first  few  days  suggested  to  Muller 
that  it  was  very  likely  that  two  factors  should  be  taken 
into  consideration;  first,  perseveration,  or  the  memory 
after-image,  which  diminishes  very  rapidly  and  may  be 
regarded  as  disappearing  in  the  first  two  days  or  so,  and, 
second,  the  associative  tendency,  which  in  accordance 
with  Jost's  law  is  to  be  conceived  as  increasing  in  strength 
for  two  days  or  more  and  then  decreasing  in  strength  very 
slowly.  For  most  purposes  the  increase  in  the  strength 
of  the  associative  tendency  is  masked  in  the  total  curve 
by  the  rapid  decrease  of  the  perseverative  tendency,  but 
later  the  decrease  in  the  strength  of  association  is  repre- 
sented by  the  curve  of  forgetting  (Fig.  92). 

Retroactive  Inhibition.  —  The  one  factor  which  seems  to 
influence  the  retention  or  forgetting  process  is  the  series  of 
events  which  take  place  in  the  few  minutes  immediately 
following  learning.  Mtiller  and  Schumann  were  the  first 
to  observe  that  learning  a  second  series  of  syllables  im- 
mediately after  the  first  decreased  the  hkelihood  of  recalling 
the  first.  The  interval  within  which  the  second  may  inter- 
fere with  retention  is  about  six  minutes.  The  degree  of 
interference  seems  to  increase  with  the  similarity  of  con- 
tent between  the  two  series,  but  any  mental  work  will  be 
injurious  within  that  period.  The  effect  is  greater  when 
the  individual  is  fatigued  or  in  periods  of  lessened  effective- 
ness, and  is  also  greater  when  the  first  has  not  been  too 
well  learned.  The  explanation  of  the  phenomenon  is  that 
the  associations  are  being  strengthened  during  the  period 
of  perseveration  that  immediately  follows  the  learning. 
If  attention  is  turned  to  anything  else,  the  perseveration 
is  interfered  with,  and  so  associations  are  less  likely  to  be 
formed.     Memories  may  also  be  prevented  from  '  setting  ' 


LAWS  OF  FORGETTING  383 

by  a  physical  or  mental  shock  of  sufficient  severity.  Fre- 
quently after  an  accident  one  remembers  nothing  of  the 
events  that  immediately  preceded  the  accident  and  nothing 
of  the  injury  itself.  The  shock  of  the  injury  will  wipe  out 
the  effects  of  the  preceding  events.  This  retroactive  in- 
hibition is  another  instance  in  which  we  have  evidence  of 
the  influence  of  the  perseveration  through  the  continuing 
activity  of  the  cortical  cells  after  the  stimulation  ceases. 

Is  Forgetting  ever  Complete?  —  It  is  evident  from  these 
studies  that  associations  persist  when  there  is  httle  imme- 
diate awareness  of  them,  when  one  cannot  bring  them  back 
by  an  associate  closely  connected  with  them;  when  they 
can  be  detected  only  from  the  fact  that  they  may  be  re- 
learned  more  easily  than  if  they  had  not  previously  been 
learned.  This  fact  has  given  rise  to  much  discussion  as  to 
whether  anything  is  ever  forgotten.  The  discussion  arose 
originally  from  the  fact  that  occasionally  long-forgotten 
events  from  a  remote  past  are  recalled.  Coleridge  cites 
the  case  of  a  girl,  a  servant  in  the  house  of  a  pastor  who 
was  accustomed  to  walk  up  and  down  a  passageway  near 
the  kitchen  where  she  was  employed,  reciting  passages 
from  Greek,  Latin,  and  Hebrew  authors.  Some  years 
later  in  a  delirium  of  fever  she  was  heard  to  recite  strange 
words  that  convinced  her  attendants  that  she  was  possessed 
of  a  devil.  The  physician  wrote  them  down  and  traced 
them  to  works  in  the  possession  of  the  old  pastor,  now 
some  years  dead.  If  the  case  is  to  be  accepted,  memories 
that  never  were  consciously  developed,  and  which  should 
have  been  forgotten  if  they  ever  had  been  developed,  may 
still  be  lying  dormant  in  the  nervous  system.  Numerous 
other  cases  may  be  cited  of  the  return  of  experiences  long 
forgotten,  usually  in  case  of  disease,  under  hypnosis,  or  in 
similar  abnormal  conditions.     These  cannot  be  taken  to 


384        FUNDAMENTALS  OF  PSYCHOLOGY 

prove  the  thesis  for  which  they  are  adduced,  but  they  may 
serve  to  reenforce  the  statement  that  experiences  leave 
their  effect  for  some  time  after  they  can  no  longer  be  re- 
called through  associations  of  ordinary  strength.  Not 
improbably  the  nervous  system  never  altogether  loses 
some  trace  of  them.  This  fact  is  of  more  importance  in 
explaining  recognition,  the  control  of  belief,  and  similar 
processes,  in  understanding  which  we  must  appeal  to  the 
effect  of  experiences  not  definitely  conscious  at  the  moment, 
than  as  a  contribution  to  the  understanding  of  retention 
and  recall.  Memories  constantly  grow  weaker  at  a  rate 
that  depends  upon  their  meaning  and  interest,  and  gradu- 
ally, if  not  refreshed,  reach  the  stage  at  which  they  cannot 
be  revived. 

Recall 

Recall,  as  was  seen  in  Chapter  VIII,  is  always  through 
association  under  the  control  of  the  wider  purpose  of  the 
moment  and  of  other  less  conscious  factors  that  constitute 
the  mental  attitude  or  context.  To  recall  any  old  event 
it  is  necessary  to  have  some  idea  which  is  in  some  way 
connected  with  that  event  or  has  some  element  in  common 
with  it.  If  we  assume  the  possession  of  a  definite  memory 
with  a  large  number  of  connections,  some  one  of  the  con- 
nections must  become  conscious  before  the  memory  itself 
will  make  its  appearance.  Usually  the  desire  to  remember 
is  either  itself  an  associate  of  the  memory  desired  or  both 
are  connected  with  a  common  idea.  Thus,  when  one  is 
asked  a  question  in  an  examination,  the  question  has  been 
connected  with  the  answer  and  serves  or  should  serve  to 
recall  it.  The  course  of  the  association  is  determined  by 
the  setting,  the  context  of  the  question  is  supplied  by  the 
subject  in  which  the  examination  is  held.    In  practical  life 


RECALL  385 

the  occasion  for  the  recall  is  a  need  for  the  bit  of  knowledge. 
A  face  presents  itself  and  one  knows  that  the  name  will  be 
needed  when  it  becomes  necessary  to  make  an  introduction; 
or  one  is  reading  of  the  size  of  a  ship  in  metres,  and  wonders 
how  long  it  is  in  feet,  and  must  recall  the  table  of  equiva- 
lents. In  each  case  there  is  always  something  that  makes 
it  desirable  to  know  the  thing  to  be  recalled,  and  this  has 
also  been  associated  with  the  fact.  Not  all  associates  of  an 
idea  are  actually  recalled.  The  reason  for  this  is  usually 
that  the  right  context  is  lacking.  One  may  read  of  the 
length  of  the  ship  in  comparison  with  other  ships  whose 
lengths  are  also  given  in  metres,  and  as  relative  size  is  all 
that  is  necessary,  the  thought  of  the  equivalent  does  not 
occur  to  one.  The  mental  attitude  or  need  of  the  moment 
always  plays  a  predominant  part. 

Reproductive  Inhibition.  —  Interesting,  if  relatively  un- 
usual, are  the  instances  in  which  one  has  occasion  for  a 
fact,  is  sure  that  it  is  known,  perhaps  well  known,  but  in 
which  one  cannot  recall  it.  One  may  be  asked  the  name  of  a 
famous  painter,  and  find  to  one's  astonishment  that  it  cannot 
be  recalled,  torture  one's  memory  for  it  as  one  may.  Fre- 
quently after  the  occasion  for  it  has  passed,  it  will  come 
back  without  the  least  difficulty,  often  when  thinking  of 
something  entirely  different.  Phenomena  of  this  sort  seem 
to  fall  under  the  head  of  reproductive  inhibition  that  was 
established  by  Miiller  and  Schumann  and  confirmed  by 
Shepard  and  Vogelsonger.  It  was  found  that,  when  two 
syllables  were  learned  at  different  times  in  connection  with 
one  single  first  syllable,  there  was  not  merely  an  obstruction 
to  the  formation  of  the  second  association  through  the  earlier 
formation  of  the  first,  but  also  an  inhibition  of  the  recall 
of  both  when  the  common  first  member  of  each  pair 
was  shown.    The  time  required  for  the  recall  of  either  is 


386        FUNDAMENTALS   OF  PSYCHOLOGY 

much  increased,  while  the  percentage  of  times  that  either 
will  be  recalled  correctly  is  correspondingly  decreased.  It 
seems  probable  that  something  Hke  this  happens  in  the 
moments  of  blocked  recall  of  familiar  facts.  The  associa- 
tions must  be  present,  as  is  shown  by  the  later  recall;  but 
apparently  too  many  associates  strive  for  entrance,  and 
each,  through  some  neural  interference,  blocks  the  way  of 
the  other.  It  should  be  added  that  there  is  some  evi- 
dence, obtained  by  Bair'-  in  his  experiments  on  learning 
typewriting,  that  when  a  series  of  associates  has  been  fully 
learned  —  when  one  keyboard  of  the  typewriter  has  been 
thoroughly  mastered  —  another  can  be  learned  in  less 
time  and  there  is  no  interference  between  them  on  recall. 
Were  this  not  true,  there  would  always  be  interference.  A 
blocking  of  recall  would  be  much  more  frequent  than  we 
find  it,  since  practically  every  bit  of  knowledge  has  many 
associates  that  might  be  recalled.  The  effect  of  the  purpose 
or  attitude  is  usually  sufficient  to  prevent  inhibition.  When 
the  context  favors  one  associate  much  more  than  another, 
the  way  is  cleared  for  it  and  all  others  are  kept  from  inter- 
fering. Interference  comes  when  the  associations  are  not 
fully  formed,  are  relatively  weak,  or  no  strong  purpose  is 
dominant. 

Learning  and  retention  depend  upon  the  formation  of 
associations  and  the  degree  in  which  they  persist,  and  recall 
is  Hkewise  through  the  connections  that  are  formed  in 
learning.  It,  too,  is  largely  a  mechanical  process,  dependent 
upon  the  relative  strength  of  the  associations,  guided  only 
by  the  context  and  the  purpose  of  the  moment.  The  laws 
that  have  been  given  are  statements  of  the  conditions  under 
which  the  associations  may  be  formed  with  greatest  strength 

1  J.  H.  Bair,  The  Practice  Curve,  Psychological  Rev.  Mon.  Supplements 
No.  19. 


RECOGNITION  387 

and  in  the  shortest  time,  together  with  an  enumeration  of 
the  factors  that  influence  retention  and  the  course  of  for- 
getting, and  the  laws  of  recall.  These  conclusions  are  of 
value  in  practice,  since  the  laws  hold  not  only  under  experi- 
mental conditions  and  for  nonsense  syllables,  but  also  for 
sense  material  under  conditions  of  ordinary  learning.  But 
in  addition  to  these  laws  which  apply  to  the  raw  materials 
of  memory,  the  fact  that  memory  ordinarily  deals  with 
things  as  real  introduces  the  elements  of  meaning  and  logical 
interconnection,  two  factors  which  are  important  in  deter- 
mining the  ease  of  learning  and  recall  and  the  use  to  be  made 
of  ideas.  The  most  important  influence  of  meaning,  in 
fact  what  first  gives  meaning  to  groups  of  centrally  excited 
sensations,  is  recognition.  By  recognition  we  mean  that 
the  idea  has  been  accepted  and  given  a  place  in  the  experi- 
ence of  the  individual.  It  is  this  in  large  measure  that  trans- 
forms the  raw  materials  into  ideas,  into  objects  and  events 
that  have  a  real  relation  to  the  past  life  of  the  individual  and 
to  his  knowledge. 

Recognition 

It  was  said  in  an  earlier  chapter  that  practically  all 
mental  processes  follow  the  pattern  of  action  in  consisting 
of  two  distinct  parts,  one  like  the  'trial  and  error'  learning 
of  a  new  movement  which  induces  the  state,  and  the  other 
a  process  which  examines  the  state  and  either  accepts  or 
rejects  it.  Recall  provides  the  material  in  memory,  recog- 
nition is  the  process  of  accepting  or  rejecting.  It  affirms 
or  denies  in  part  by  assigning  a  date,  —  by  referring  the 
experience  to  the  time  and  place  of  its  original  appearance. 
This  is  in  itself  a  warrant  for  the  truth  of  the  recalled  pro- 
cess. Thus  in  an  examination  many  ideas  may  be  suggested 
one  after  another,  as  the  answer  to  a  question  of  fact.    If 


388        FUNDAMENTALS   OF  PSYCHOLOGY 

questioned,  it  is  usually  not  until  the  idea  can  be  assigned  to 
a  particular  book  or  to  a  particular  lecture  that  it  will  be 
accepted  as  sufficiently  assured  to  put  down.  Recall  must 
be  tested  and  confirmed  by  recognition  before  memory  is 
complete. 

The  Process  of  Recognition.  —  Recognition  appHes  to 
objects  as  well  as  to  ideas  or  memories,  and  may  be  studied 
equally  well  with  one  or  the  other.  When  one  sees  a  person 
one  must  decide  whether  he  is  an  acquaintance  or  a  stranger, 
before  one  speaks;  and  if  he  proves  to  be  an  acquaintance 
and  he  approaches,  it  is  convenient  to  know  the  name  and 
where  he  was  seen  before.  The  process  of  recognition  may 
in  itself  be  nothing  more  than  the  arousal  by  association 
of  his  name  or  of  the  place  where  he  was  last  seen,  or  of  the 
topic  discussed  with  him  at  the  last  meeting.  When  these 
associates  present  themselves  one  is  said  to  recognize. 
The  explicitness  of  the  recognition  depends  upon  the 
definiteness  of  the  associations  that  come  to  cluster  about 
the  face.  Memories  are  recognized  in  much  the  same  way. 
When  the  idea  is  recalled,  secondary  ideas  are  aroused 
which  give  the  first  a  setting  and  a  warrant. 

An  objective  study  of  the  phenomena  of  recognition  adds 
much  that  must  be  considered  in  any  theory.  As  compared 
with  recall,  recognition  is  as  a  rule  easier  and  induced  by 
fewer  repetitions.  A  student  will  frequently  recognize  an 
answer  when  given  by  another  in  a  recitation  after  he  has 
himself  failed.  It  is  easier  to  learn  nonsense  syllables  to 
the  point  where  they  may  be  recognized  when  shown  than  to 
the  point  where  they  may  be  repeated.  On  the  other  hand, 
one  frequently  finds  in  pathological  cases  that  recognition 
is  disturbed  while  recall  is  still  almost  unimpaired.  This 
is  seen  in  psychasthenia,  and  in  certain  cases  of  insanity, 
particularly  in  Korsakoff's  disease.     The  psychasthenic  at 


RECOGNITION  389 

times  will  find  everything  strange,  at  other  times  will 
recognize  objects  and  people  that  have  never  been  seen 
before.  Everything  seems  strangely  familiar  to  the  patient. 
It  seems  that  recognition  is  a  rather  more  certain  process 
than  recall  in  the  normal  individual,  but  is  more  easily 
disturbed  in  the  abnormal ;  in  fact  it  is  often  the  first  process 
to  be  disturbed  in  mental  deterioration.  It  is  also  less 
affected  by  work  performed  after  the  learning  —  by  retro- 
active inhibition  —  than  is  recall.  In  some  ways,  then,  it 
seems  more  easy  to  induce  recognition  than  recall,  but  at 
the  same  time  recognition  is  more  dehcate  as  measured  by 
the  susceptibility  to  impairment  by  disease,  but  is  not  so 
readily  disturbed  by  mental  work  immediately  following. 

Experimental  Studies  of  Recognition.  —  Experiments 
were  early  made  and  have  been  frequently  repeated  on  the 
effects  of  the  passage  of  time  upon  the  accuracy  of  recog- 
nition. The  results  fall  into  two  distinct  classes  which  may 
be  represented  by  two  of  the  earhest  workers,  Wolfe  and 
Lehmann.  Both  sought  to  determine  the  influence  of  the 
lapse  of  time  upon  the  accuracy  of  recognition.  Wolfe^ 
worked  with  tones  which  could  be  made  to  differ  by  as  little 
as  four  vibrations,  and  had  a  number  of  tones  at  his  com- 
mand, so  that  they  could  not  be  readily  referred  to  a  class 
or  given  a  distinguishing  name.  He  found  that  capacity  to 
recognize  diminished  with  the  passage  of  time,  at  almost  the 
same  rate  as  the  ability  to  recall.  His  curve  showed  the 
same  form  as  Ebbinghaus'  curve  of  forgetting;  recognition 
fell  off  rapidly  at  first  and  much  more  slowly  later.  Leh- 
mann^  used  gray  papers  of  different  shades.  At  first  he 
used  five  shades.  His  subjects  at  once  arranged  these  in  a 
series  and  gave  a  definite  name  to  each.    His  results  showed 

1  Wolfe,  Philosophische  Studien,  Vol.  3,  p.  534. 
*  Lehmann,  Phil.  Stud.,  Vol.  5,  p.  96. 


390        FUNDAMENTALS   OF  PSYCHOLOGY 

almost  no  tendency  to  diminution  of  accuracy  with  the 
passage  of  time.  At  first  the  judgments  increased  sKghtly 
in  accuracy  and  then  declined  shghtly,  but  there  was  no 
approach  to  the  logarithmic  curve  obtained  by  Ebbinghaus. 
When  Lehmann  introduced  nine  shades,  these  were  given 
numbers  from  one  to  nine,  and  the  curve  retained  the  same 
form.  Later  investigations  by  Angell  and  Hayward^  and 
by  Hayden^  under  approximately  the  same  conditions 
have  given  results  similar  to  Lehmann's.  The  difference 
in  the  results  obtained  by  Wolfe  and  the  others  may  be 
attributed  to  the  degree  in  which  the  material  makes  possi- 
ble the  association  of  a  word  or  other  famihar  symbol. 
Where  no  such  symbol  may  attach,  recognition  is  difficult, 
and  abihty  to  recognize  vanishes  very  quickly.  When  the 
symbol  may  be  applied,  recognition  is  immediate  and  per- 
sists for  some  time  with  no  appreciable  diminution.  Back 
of  the  assignment  of  the  name  or  number  is  the  develop- 
ment of  a  definite  image  or  notion  of  the  different  impres- 
sions to  be  recognized  that  shall  make  it  stand  out  for  itself 
and  so  shall  constitute  a  fixed  standard. 

This  difference  between  the  results  obtained  by  Wolfe 
and  those  obtained  by  the  others  is  similar  to  the  difference 
between  results  with  nonsense  and  sense  material.  A 
number  of  recent  experiments  by  Holhngworth,  Miss 
Mulhall,  Strong,  and  others,  showed  the  same  difference  in 
ease  of  recognition  between  material  that  has  and  that 
which  has  not  meaning.  They  found  in  the  first  place  that 
recognition  was  much  more  certain  and  persisted  longer  than 
ordinary  recall.  It  was  from  two  to  three  times  as  accurate 
as  recall  when  advertisements,  pictures,  words,  or  other 
sense  material  was  used.     But  with  nonsense  syllables, 

1  Angell  and  Hayward,  American  Journal  of  Psychology,  Vol.  ii,  p.  67. 

2  Hayden,  American  Journal  of  Psychology,  Vol.  17,  p.  497. 


RECOGNITION 


391 


recognition  had  very  little  if  any  advantage  over  recall. 
If  we  apply  this  to  our  other  problem,  it  is  evident  that 
recognition  of  meaningful  material  has  a  very  great  advan- 
tage over  recognition  of  nonsense  material.  In  the  one  case 
the  shades  of  gray  could  be  immediately  connected  with 
words  that  had  either  a  definite  meaning  acquired  long 
before  the  experiments  were  begun,  or  that  could  be 
quickly  developed  for  the  few  shades  used.  One  association 
alone  needed  to  be  formed  in  order  to  assure  recognition 
in  each  experiment.  Recognition  itself  required  no  more 
than  a  decision  whether  the  shade  offered  did  or  did  not 
correspond  to  the  standard  required.  In  Wolfe's  experi- 
ments, no  standards  were  present  at  the  beginning  and  none 
could  be  readily  developed  because  of  the  great  number  of 
tones  used,  and  the  slight  differences  in  pitch  that  were 
available.  Here  one  dealt  with  bare  association  processes 
formed  during  the  experiments  between  sensations,  neither 
of  which  had  a  meaning  of  its  own.  All  the  preparation  for 
recognition  must  be  made  during  the  experiment,  while  in 
the  experiments  with  meaningful  material,  most  of  the 
preparation  was  completed  before  the  experiments  were 
begun.  Meaning,  then,  contributes  much  to  the  ease  and 
persistence  of  recognition. 

Forms   of   Recognition.  —  Investigators   have  classified 
the  different  varieties  of  recognition. 

We  may  regard  as  complete  recognition  a  feeling  of 
assurance  as  to  the  place  where  the  object  was  seen 
before,  and  a  recall  of  all  the  circumstances  of  that 
earher  experience.  This  is  called  definite  as  opposed 
to  indefinite  recognition. 

In  the  latter  case,  one  is  aware  that  the  thing  is 
familiar  but  can  assign  no  definite  place  to  it.  Many 
faces  are  familiar  which  arouse  no  name,  and  cannot 


392        FUNDAMENTALS   OF  PSYCHOLOGY 

even  be  referred  to  a  specific  time  or  place.  This 
indefinite  recognition  is  ordinarily  due  to  slight 
familiarity. 

At  the  other  extreme,  things  which  are  very  familiar 
are  also  recognized,  but,  because  of  their  great  famil- 
iarity, are  referred  to  no  definite  place.      Here  the 
recognition  is  taken  for  granted.    This  happens  with 
the  furniture  of  a  well-known  room,  with  intimate 
friends,  and  with  events  that  are  frequently  recalled. 
It  is  an  implicit  as  opposed  to  an  expHcit  recognition. 
The  objects  are  treated  as  if  known,  arouse  a  feehng 
that  is  different  from  that  aroused  by  strange  objects, 
but  are  seldom  referred  to  earlier  times  or  even  named. 
Still  another  distinction  must  be  drawn  with  reference  to 
the  way  in  which   recognition   takes  place.     In    certain 
instances  one  can  see  how  the  recognition  goes  on.     A 
hauntingly  familiar  memory  makes  its  appearance,  but  it 
has  no  connections  and  can  be  given  no  place.    Gradually, 
as  one  broods  over  it,  other  things  are  called  up  by  it.    Then 
suddenly  an  associate,  itself  familiar,  is  added  to  it,  and 
recognition   is    complete.     This   may   be   called   mediate 
recognition,    as    opposed    to    the    immediate    recognition 
which  is  much  more  usual.     As  will  be  seen,  all  of  these 
types  have  common  laws.     Those   mentioned    later   are 
reductions  from  the  complete  form. 

The  Association  Theory  of  Recognition.  —  Theories  of 
recognition  are  very  numerous  and  in  some  degree  con- 
flicting. One  has  been  already  indicated,  the  placing  of 
the  unknown  through  association  with  the  known.  This 
can  be  traced  empirically  very  frequently.  One  hears  the 
title  of  a  book;  it  sounds  familiar,  but  can  be  given  no 
place.  Gradually,  ideas  cluster  about  it  until  it  is  placed 
as  a  novel  by  such  an  author,  read  on  the  boat  two  years 


RECOGNITION  393 

ago;  or  it  may  be  remembered  as  the  book  that  was  recom- 
mended by  Jones  but  which  has  not  been  read.  Similarly 
with  the  recognition  of  objects.  This  bit  of  crystal  at  first 
seems  to  be  absolutely  unknown;  then  a  background  grows 
up  about  it;  you  remember  where  it  came  from;  that  sup- 
plies the  name  and  the  purpose  for  which  you  obtained  it, 
and  the  whole  recognition  is  complete.  The  association 
theory  assumes  that  all  recognition  is  of  this  type,  and  that 
in  the  cases  in  which  the  recognition  is  indefinite  the  asso- 
ciates are  present  and  have  their  effect,  although  they  are 
overlooked  or  do  not  come  to  full  consciousness.  They 
nevertheless  provide  the  mark  of  familiarity,  give  a  color 
to  consciousness  that  is  accepted  as  a  warrant  for  the  belief 
that  the  idea  or  object  has  been  experienced  before. 

Unnoticed  Associates  May  Induce  Recognition.  —  Even 
in  immediate  recognition  the  associations  give  the  quahty  of 
famiHarity.  Probably  the  feehng  of  familiarity  is  due  in 
the  case  of  these  very  frequently  repeated  objects  and  events 
to  partially  open  association  paths  that  give  recognition 
without  any  definite  recall  of  the  associated  events.  When 
the  object  is  famihar  but  cannot  be  definitely  placed,  it  is 
probable  that  there  are  also  partially  open  association  paths, 
but  that  they  do  not  lead  to  the  meaningful  object  or  to  the 
fixed  landmark.  The  feehng  is  present  with  nothing  to  fix 
the  experience.  Similarly,  in  certain  cases  in  which  the 
recognition  is  false,  when  one  sees  an  individual  who  seems 
familiar  but  on  speaking  finds  that  he  is  not  an  acquaint- 
ance, it  is  probable  that  something  in  the  person  suggests 
another  or  calls  up  associates  that  are  misplaced.  Here  the 
associates  give  the  feeling  without  even  warrant  in  fact. 
In  short,  partially  open  association  paths  give  the  feeling 
of  famiUarity  when  recognition  is  not  complete  and  even 
when  the  recognition  is  not  objectively  true. 


394        FUNDAMENTALS   OF  PSYCHOLOGY 

The  Motor  Theory.  —  Another  theory  with  many  adher- 
ents is  that  the  feehng  of  familiarity  comes  from  slight 
movements  awakened  by  the  stimulus  or  image.  This  is 
approximately  the  same  theory  as  the  other,  except  that 
the  processes  aroused  are  first  motor,  then  sensory.  The 
idea  arouses  some  habitual  movement,  sKght  or  more  in- 
tense, and  this  constitutes  the  basis  of  the  assurance  that  the 
object  has  been  seen  before.  The  movements  themselves 
are  not  recognized,  but  because  of  their  arousal  the  famil- 
iarity attaches  at  once  to  the  object.  The  best  instance  of 
this  is  to  be  found  in  the  feehng  of  '  at  homeness  '  that 
comes  with  the  use  of  an  old  tool  or  instrument  when  one 
comes  back  to  it  after  a  period,  as  compared  with  the  feehng 
of  a  strange  one,  even  if  it  is  of  the  same  pattern.  The 
habits  that  have  been  developed  in  its  use  are  suited  to  it, 
and  the  pleasant  feehng  of  familiarity  results. 

The  Feeling  Theory  of  Recognition.  —  Another  group  of 
theories  starts  with  the  assumption  that  recogriition  is  an 
immediate  experience  that  cannot  be  analyzed  or  explained, 
but  must  either  be  accepted  as  a  given  fact  or  be  speculated 
about  in  general  terms.  The  more  definite  of  these  theories 
asserts  that  recognition  comes  because  of  the  pleasure 
which  attaches  to  the  famihar  experience  as  compared  with 
the  unpleasantness  or  neutral  quahty  of  the  unknown. 
The  pleasure  is  explained  as  the  result  of  an  instinct.  The 
known  is  pleasant,  since  one  always  makes  an  immediate 
response  to  it.  If  harmful,  one  can  avoid  it  immediately; 
if  beneficial,  it  is  pleasant  in  and  of  itself.  The  objection 
to  the  theory  is  based  primarily  on  fact.  Not  all  cases  of 
recognition  are  pleasant,  certainly  not  all  pleasant  things 
are  famihar.  Another  theory  in  this  group  asserts  that 
famiharity  is  an  immediate  conscious  experience,  even  more 
primary  than  either  sensation  or  association.    This  theory 


RECOGNITION  395 

represents  a  possible  interpretation,  if  all  others  fail.  The 
same  objections  hold  against  it  as  those  raised  against  na- 
tivism  in  space.  It  gives  up  the  problem  without  attempt- 
ing an  explanation. 

The  Advantages  of  the  Association  Theory.  —  The  evi- 
dence so  far  accumulated  favors  the  association  theory  in 
some  form.  Indirect  recognition  can  be  traced  to  associa- 
tions. In  direct  or  immediate  recognition,  we  cannot  de- 
tect associations  exphcitly.  Nevertheless,  three  facts  in- 
dicate that  they  must  be  present,  (i)  Things  that  have 
many  associates  are  readily  recognized,  while  nonsense  ma- 
terial —  that  is,  material  without  associates  —  is  recognized 
with  difficulty,  is  recognized  no  more  easily  than  it  is  re- 
membered. Recognition  is  aided  also  by  two  of  the  factors 
that  aid  association.  (2)  Meyer  showed  that  recognition 
of  nonsense  syllables  was  more  accurate  when  a  syllable 
with  which  it  had  previously  been  associated  was  shown, 
just  before  the  syllable  to  be  recognized  was  presented. 
(3)  It  has  been  proven,  too,  that  recognition  is  quicker  and 
more  accurate  if  the  individual  is  in  the  proper  attitude 
toward  the  object  to  be  recognized  just  before  it  is  shown. 
Just  as  in  everyday  life,  if  one  meet  an  old  acquaintance, 
when  one  has  been  thinking  about  the  place  where  he  was 
known,  one  is  very  much  more  hkely  to  recognize  him  than 
if  he  appears  without  any  preparation.  These  four  facts 
together  indicate  that  association  and  recognition  are  very 
closely  related.  Recognition  always  comes  when  associates 
are  aroused,  and  where  associates  are  not  overtly  present, 
experiments  indicate  that  conditions  which  favor  the  for- 
mation of  associates  or  recall  by  association  also  favor 
recognition. 

Meaning  and  Recognition.  —  In  any  statement  of  the 
association  theory  of  recognition,  it  is  taken  for  granted 


396        FUNDAMENTALS   OF  PSYCHOLOGY 

that  the  associates  must  be  themselves  familiar  or  the 
process  will  not  be  complete.  Sometimes  several  links  are 
necessary  before  a  familiar  associate  presents  itself.  The 
familiarity  that  attaches  in  turn  to  the  associates  effective 
for  recognition  and  also  to  the  objects  recognized  immedi- 
ately is  itself  due  to  associates.  The  dilTerence  between  the 
mediate  and  the  immediate  is  another  expression  of  the 
difference  between  the  two  sorts  of  recognition  that  distin- 
guished the  methods  used  by  Wolfe  and  by  Lehmann.  In 
Lehmann's  form  the  new  is  related  to  some  established 
type,  to  something  that  has  been  used  so  frequently  and 
recalled  so  often  that  it  has  become  firmly  established  and 
thoroughly  famihar.  These  are  accepted  at  once  and  with- 
out question.  They  are  the  types  that  we  found  necessary 
to  explain  perception,  and  are  also  the  concepts  that  play 
an  essential  part  in  reasoning.  Probably  these  fixed  points 
of  reference  for  our  knowledge  are  also  established  and  re- 
ceive recognition  through  the  numerous  associates  that 
they  tend  to  arouse  but  which  do  not  become  explicit. 
Your  own  name,  to  take  an  extreme  case,  is  established 
more  firmly  in  your  mind  than  the  name  of  another,  be- 
cause of  the  number  of  times  it  has  been  associated  with 
yourself  and  with  other  experiences.  Certain  events  be- 
come landmarks  in  all  memory  and  may  be  used  as  points 
of  reference  because  of  the  number  of  associates  that  have 
been  made  with  them,  and  through  their  frequent  recall  in 
different  connections.  When  an  event  that  is  at  first  un- 
placed can  be  attached  to  one  of  these  firmly  established 
incidents,  it  at  once  takes  on  something  of  its  familiarity, 
in  the  same  way  that  assignment  of  the  name  was  all  that 
was  necessary  in  Lehmann's  experiments  to  constitute 
recognition  of  the  shade. 

Recognition    and    Cognition.  —  Recognition   is   largely 


MEANING   AN   AID    TO   MEMORY         397 

aided  by  the  types  that  were  found  so  important  in  per- 
ception, and  also  by  meaning,  a  process  fundamental  to 
thinking  of  all  sorts.  The  part  played  by  the  type  and 
by  meaning  may  be  seen  more  clearly  in  the  more  general- 
ized form,  cognition.  Here  objects  are  referred  to  classes 
rather  than  to  particular  times  or  places.  It  is  more  fre- 
quent than  recognition.  We  are  constantly  referring  all 
objects  that  come  under  our  notice  to  a  class.  Natural 
objects  are  named,  tools  related  to  their  uses,  people  are 
assigned  to  different  races  or  classes  when  they  are  not 
acquaintances.  This  process  of  cognition  differs  from  rec- 
ognition only  in  that  there  is  no  reference  to  the  earlier 
experience  of  the  individual,  no  awareness  that  the  thing  has 
ever  before  been  seen.  Except  for  determining  ownership 
of  objects  and  for  our  relations  with  people,  it  is  seldom 
that  we  need  to  do  more  than  cognize.  Cognition  differs 
from  recognition  solely  in  that  the  reference  is  to  some 
class  only,  some  type  of  objects,  with  no  reference  to  per- 
sonal knowledge.  The  process  involves  the  same  factors; 
a  general  notion  always  serves  as  the  point  of  attachment, 
but  this  has  a  more  or  less  marked  series  of  associations 
that  irradiate  from  it  to  give  appreciation  of  its  use,  or  of 
its  special  characteristics.  In  almost  every  respect  it  is  like 
the  type  or  concept  which  we  saw  to  be  evoked  in  percep- 
tion, and  which  constitutes  what  we  accept  as  the  real  ob- 
ject. Cognition  is  a  reference  of  the  particular  object  or 
memory  image  to  a  similar  typical  object  or  class.  Mem- 
ory is  like  perception  in  that  it  deals  with  real  objects  or 
concepts,  rather  than  with  mere  centrally  aroused  sensations. 

Meaning  an  Aid  to  Memory 

Meaning  in  Learning.  —  Meaning  is  not  only  a  factor  in 
making  recognition  possible  but  is  also  an  important  fac- 


398        FUNDAMENTALS   OF  PSYCHOLOGY 

tor  in  all  learning.  The  meaning  that  the  material  to  be 
learned  has  for  the  individual  determines  in  very  large 
degree  how  quickly  it  may  be  learned  and  how  long  it  shall 
be  retained.  The  difference  in  the  amount  of  time  re- 
quired for  learning  and  the  degree  of  retention  between 
sense  and  nonsense  material  is  very  striking.  This  may  be 
seen  both  in  primary  memory  and  in  learning  long  series. 
Ebbinghaus  found  that  school  children  could  give  only  five 
of  seven  nonsense  syllables,  while  of  a  sentence  of  38  words 
containing  seventeen  separate  ideas,  they  could  remember 
fifteen  of  the  ideas.  For  himself  he  found  that  with  the 
same  number  of  repetitions  he  could  remember  eight  or 
nine  times  as  great  a  quantity  of  simple  poetry  as  of  non- 
sense syllables.  Meumann  obtained  slightly  smaller  values, 
7-9  nonsense  syllables,  13  words  or  numbers,  20  words  of 
a  poem,  and  24  of  philosophical  prose. 

Meaning  not  only  aids  in  learning  but  also  assures  a 
greater  persistence  of  the  material  that  is  learned.  The 
material  learned  is  much  less  readily  forgotten.  Ebbing- 
haus demonstrated  the  fact  for  rote  memory  of  verse.  In 
some  of  his  earlier  experiments  he  used  a  translation  of 
Byron's  "Don  Juan."  After  twenty-two  years,  he  found 
that  he  could  detect  a  saving  of  7  per  cent  in  the  time  re- 
quired for  relearning  stanzas  as  compared  with  learning 
new  stanzas.  After  seventeen  years  there  was  a  saving  of 
20  per  cent  in  relearning  stanzas  which  had  originally  been 
learned  on  four  successive  days.  This  is  to  be  compared 
with  a  saving  of  20  per  cent  for  nonsense  syllables  at  the 
end  of  thirty  days.  The  retention  of  ideas  is  still  more 
complete.  General  principles,  or  even  interesting  events, 
are  frequently  recalled  after  the  greater  part  of  a  lifetime. 
Here,  however,  there  is  usually  repetition  or  recall  in  the 
intervening  years. 


MEANING  AN  AID  TO  MEMORY  399 

Meaning  Due  to  Grouping  and  to  Reference  to  Systems 
of  Experiences.  —  Two  reasons  may  be  found  for  the 
greater  ease  of  learning  meaningful  material.  First,  that 
to  gain  meaning  the  different  partial  experiences  must  be 
grouped  about  a  single  centre,  must  be  combined  into 
units,  and  these  units  are  then  remembered  practically  as 
single  elements.  In  some  recent  investigations  of  a  Hght- 
ning  calculator,  Dr.  Ruckle,  G.  E.  Miiller  found  that  an 
essential  element  of  his  ability  to  make  calculations  very 
quickly  was  his  capacity  for  remembering  figures,  and  that 
this  in  turn  was  due  to  an  abihty  to  unite  the  figures  into 
small  groups.  Ruckle  could  retain  and  repeat  in  any  order 
forty-nine  digits.  He  saw  them  arranged  in  seven  columns 
of  seven  digits  each.  The  seven  series  seemed  to  count  for 
him  as  seven  single  units.  A  second  element  in  acquiring 
meaning,  well  illustrated  by  this  same  investigation,  is  the 
attachment  of  the  thing  to  be  remembered  to  elements  of 
experience  already  firmly  fixed,  —  an  interpretation  in  the 
light  of  old  knowledge.  Ruckle  related  many  of  the  num- 
bers that  he  could  remember  to  combinations  of  numbers 
with  which  he  was  already  famihar.  Thus  he  remembered 
451,697,  because  it  was  made  up  of  the  multiples  of 
two  prime  numbers:  451  =  11X41,697  =  17X41-  Six  hun- 
dred and  twenty-four  was  easy,  since  it  is  the  square  of  25 
minus  i.^  With  a  large  acquaintance  with  numbers,  learn- 
ing new  ones  was  relatively  easy.  All  material  that  has 
meaning  has  these  two  qualities.  It  is  combined  into  rela- 
tively small  groups.  These  groups  are  used  over  and  over 
again  until  they  constitute  practically  a  unit  and  they  are 
learned  in  different  connections  until  firmly  established 
and  then  can  be  recalled  by  many  other  experiences. 

When  anything  has  meaning,  it  is  already  connected 
^Zeitschrift  f.  Psychologic,  Erganzungsbd.  V,  pp.  215  ff. 


400        FUNDAMENTALS  OF  PSYCHOLOGY 

with  something  that  is  a  part  of  the  fundamental  intel- 
lectual equipment  of  the  individual.  In  this,  to  have 
meaning  and  to  be  recognized  or  cognized  are  approxi- 
mately identical.  Thus  we  found  that  recognition  con- 
sisted in  attaching  to  the  object  or  idea  that  is  to  be  recog- 
nized some  mark  in  itself  famihar.  The  permanency  of 
recognition,  then,  becomes  the  permanency  of  the  older 
acquirement.  In  learning  material  that  has  meaning,  the 
same  factor  is  even  more  prominent.  When  the  meaning 
of  anything  is  understood,  it  is  by  that  very  fact  united  to 
the  already  familiar,  becomes  an  instance  under  a  general 
law  or  a  general  class,  and  that  gives  it  in  large  degree  the 
permanence  of  the  general  law.  The  meaningful  material, 
by  virtue  of  the  fact  of  having  meaning,  will  then  be  sure 
to  belong  to  a  larger  group  and  so  become  easier  to  learn, 
and  will  also  be  connected  with  something  that  is  already 
known  and  which  permits  the  new  to  be  understood.  These 
two  characteristics  alone  would  go  far  toward  explaining 
the  advantage  for  learning  of  sense  material. 

The  importance  of  meaning  can  be  seen  to  still  better 
advantage  in  the  type  of  learning  most  frequently  prac- 
tised in  adult  Hfe,  learning  the  substance  without  the 
words.  In  this  there  must  be  some  connection  with  a 
wider  knowledge,  or  nothing  can  be  retained.  Almost  any- 
thing that  is  understood  can  be  retained  for  a  little  time, 
and  to  understand  is,  in  essence,  to  connect  the  new  with 
the  previously  organized  knowledge.  The  degree  of  reten- 
tion depends  in  part  upon  frequency  of  repetition  of  the 
ideas,  but  much  more  upon  the  number  of  different  ways 
in  which  the  new  is  linked  with  the  old,  and  thus  to  the 
completeness  with  which  it  is  understood.  While  the  pro- 
cess of  understanding  is  more  important  on  the  whole  than 
the  formation  of  discrete  associations,  both  must  be  pres- 


GENERAL  ASPECTS   OF   MEMORY         401 

ent  in  some  degree.  Meaning  has  a  basis  in  association,  as 
has  been  pointed  out,  and,  on  the  other  hand,  frequent 
repetition,  even  of  nonsense  syllables,  tends  to  give  them 
some  meaning,  however  slight.  For  practical  purposes  they 
are  usually  opposed.  In  rote  learning,  only  the  associates 
between  the  elements  are  considered;  in  sense  material, 
the  connections  with  the  more  general  knowledge  are  em- 
phasized. When  one  is  learning  by  rote,  the  meaning  of 
the  material  may  be  lost  sight  of;  in  sense  learning,  the 
words  may  be  altogether  neglected.  Either  can  be  trained 
at  the  expense  of  the  other.  Individual  differences  in  the 
use  of  one  or  the  other  are  matters  of  training,  and  it  is 
possible  to  acquire  the  ability  to  use  either  at  will. 

General  Aspects  of  Memory 

Individual  Differences  in  Memory.  —  Not  merely  is 
there  a  difference  in  the  degree  to  which  rote  and  sense 
memory  may  be  used,  but  there  are  differences  in  the  ca- 
pacity of  learning  in  general  and  in  the  aptitude  for  learn- 
ing different  kinds  of  material.  One  of  the  most  discussed 
is  the  difference  between  quick  and  slow  learners.  Ebbing- 
haus  asserts  that  there  is  a  law  of  compensation  in  learn- 
ing in  that,  if  one  learns  slowly,  one  also  forgets  slowly. 
The  instances  chosen  prove  only  that  there  is  a  greater 
percentage  of  saving  for  the  slower  learners,  but  the  num- 
ber of  repetitions  required  for  relearning  is  least  with  the 
quick  learner,  and  not  so  very,  much  greater  for  those  who 
learned  more  slowly  in  the  beginning.  Later  experiments 
indicate  that  the  quick  learner  is  more  effective  in  every 
respect.  At  the  best,  then,  the  slow  learner  has  an  advan- 
tage only  in  the  percentage  of  repetitions  saved,  not  in  the 
amount  that  may  be  recalled  by  associates  or  in  the  time 
required  for  relearning.     In  several  of  the  cases  given,  a 


402        FUNDAMENTALS   OF  PSYCHOLOGY 

quick  learner  would  learn  and  relearn  twenty-four  hours 
later  in  fewer  repetitions  than  the  slow  learner  required  for 
the  first  learning. 

Dependence  upon  Age.  —  The  dependence  of  memory 
upon  age  is  fairly  well  established.  Measured  by  either 
the  memory  span,  or  the  quickness  of  learning,  or  the  im- 
mediate retention,  memory  increases  gradually  to  thirteen, 
then  improves  very  rapidly  to  sixteen,  and  then  more 
slowly  to  a  maximum  at  twenty-two  to  twenty-five,  then 
apparently  persists  approximately  unimpaired  throughout 
life,  or  at  least  until  the  onset  of  senile  decay.  Meumann 
grants  that  children  may  retain  material  once  learned 
rather  better  than  adults,  a  fact  which  accounts  for  the 
large  percentage  of  our  memories  derived  from  early  child- 
hood; but  both  immediate  memory  and  ease  of  learning 
are  greatest  after  maturity  has  been  attained.  Another 
factor  that  may  be  regarded  at  any  moment  as  an  indi- 
vidual difference,  although  it  may  depend  upon  habit,  is 
the  tendency  to  remember  meanings  or  to  remember  by 
rote.  This  accounts  for  part  of  the  apparent  advantage  of 
children.  They  are  accustomed  to  learn  by  rote,  and  for 
that  reason  do  it  relatively  better  than  do  adults,  who  are 
at  once  lost  in  the  meaning,  and  find  difficulty  in  forcing 
themselves  to  attend  to  the  words.  The  power  of  rote 
learning  can  of  course  be  cultivated,  and  adults  who  have 
cultivated  rote  learning  have  an  advantage  in  this  also. 

Dependence  upon  Types  of  Imagery.  —  Still  another 
more  truly  individual  characteristic  is  to  be  found  in  the 
dependence  of  memory  upon  sensorial  type.  An  individ- 
ual of  a  visual  type  is  probably  more  successful  in  remem- 
bering words,  colors,  landscapes,  and  similar  material;  an 
individual  of  the  auditory  type,  in  remembering  musical 
memories  of  all  sorts,  and  the  order  of  material  that  is 


GENERAL  ASPECTS   OF    MEMORY        403 

learned.  Which  type  is  absolutely  the  best  is  not  known, 
since  investigations  have  not  extended  to  a  sufficiently 
large  number  of  individuals.  Meumann  asserts  that  the 
visual  memory  is  best  for  the  retention  of  the  elements, 
but  that  the  motor-auditory  obtains  a  more  accurate  grasp 
of  the  whole.  In  the  work  of  the  arithmetical  prodigies  or 
lightning  calculators,  differences  in  memory  type  play  a 
considerable  part  in  determining  the  character  of  their 
feats.  Two  that  have  been  studied,  Diamandi  and  Dr. 
Ruckle,  were  visual  in  type,  and  one,  Inaudi,  was  auditory- 
motor.  The  motor  type  did  not  lend  itself  to  the  reversal 
of  operations,  but  with  simpler  processes  was  much  quicker 
than  the  visual.  On  the  whole  the  motor  memory  was 
quicker  as  far  as  it  went,  but  much  less  flexible  than  the 
visual  memory.  When  space  factors  entered,  the  visual 
far  outstripped  the  motor-auditory.  These  are  but  illus^ 
trations  of  differences  in  capacity  that  depend  upon  the 
memory  type. 

Economy  of  Memory.  —  If  one  be  asked  how  to  learn  to 
the  best  advantage,  or  how  to  improve  one's  memory  or 
capacity  for  remembering,  the  best  answer  is  to  apply  the 
rules  given  under  the  different  heads  of  this  chapter.  If 
material  is  to  be  learned  by  rote,  it  is  essential  that  there 
should  be  a  large  number  of  repetitions.  In  any  case  the 
repetitions  should  be  divided  over  as  many  days  as  possi- 
ble and  should  be  made  by  the  whole  method,  and  not  part 
by  part  or  bit  by  bit.  The  units  should  be  grouped  into 
wholes  as  far  as  possible,  since  this  grouping  reduces  the 
work  that  must  be  done  in  learning.  Above  all,  however, 
wherever  the  material  to  be  learned  has  any  meaning,  it  is 
essential  to  understand  it.  Material  understood  is  more 
than  half  learned.  In  the  process  of  understanding,  it  is 
well  to  approach  the  material  from  as  many  different 


404        FUNDAMENTALS   OF  PSYCHOLOGY 

points  of  view  as  possible.  The  greater  the  number  of 
points  of  attachment,  the  more  thorough  is  the  under- 
standing, and  also  the  greater  the  number  of  connections 
by  which  to  arouse  the  memory  in  recall.  Where  matter  is 
to  be  learned  by  rote  as  well  as  in  substance,  it  is  well  to 
make  two  or  three  repetitions  to  understand  the  material, 
and  then  to  proceed  to  commit  to  memory  by  repetition. 
It  is  essential  also  to  attempt  to  repeat  unaided  as  soon  as 
possible.  Usually  after  four  or  five  repetitions,  a  free  recall 
should  be  begun  and  frequent  tests  made  of  the  parts  that 
are  least  well  recalled. 

Memory  Systems.  —  Numerous  attempts  have  been 
made  since  classical  times  to  develop  methods  of  aiding 
memory.  Latin  orators  made  use  of  the  device  of  pictur- 
ing their  orations  upon  the  walls  of  different  rooms  of  a 
house,  one  part  on  each  wall  of  a  room,  and  larger  units  in 
the  same  room.  As  they  proceeded,  they  would  picture 
themselves  as  walking  through  the  house  and  reading  their 
various  headings  from  the  walls.  A  more  modern  form  of 
mnemonics,  but  one  that  goes  back  several  centuries,  con- 
sists in  forming  series  of  links,  based  upon  chance  asso- 
ciates between  any  two  things  that  are  to  be  recalled  to- 
gether. Thus  one  may  remember  that  A  is  the  Greek  let- 
ter delta  by  the  series:  triangle,  pyramid,  Nile,  Delta.  Or 
it  may  be  remembered  that  Denver  is  the  capital  of  Colo- 
rado through  the  Hugo,  Colorado,  dodo,  bird,  dense  air, 
Denver.  Similar  connections  are  made  by  these  systems 
between  any  two  facts  that  are  to  be  connected.  Obvi- 
ously any  scheme  of  this  kind  will,  in  the  long  run,  prove 
more  harmful  than  helpful,  as  it  involves  making  four  or 
five  associates  where  only  one  is  needed,  and  the  others  are 
likely  to  develop  inhibitions  as  well  as  waste  time.  It  is 
much  better  to  trust  to  forming  the  associations  directly, 


GENERAL   ASPECTS    OF   MEMORY         405 

and  better  still,  if  connections  are  needed,  to  base  them 
upon  some  fundamental  general  principle.  The  system  of 
the  sciences  is  from  one  point  of  view  merely  a  vast  mne- 
monic system,  a  means  of  bringing  a  large  number  of  iso- 
lated facts  into  connection  with  each  other  in  some  logical 
way.  To  make  use  of  that  as  a  means  of  remembering  is 
to  follow  a  plan  that  has  been  developed  by  the  best  minds 
of  all  times,  rather  than  some  chance  scheme  that  has  been 
hit  upon  by  a  charlatan. 

Transfer  of  Training.  —  A  question  of  practical  as  well 
as  theoretical  interest  is  whether  exercises  in  learning  may 
be  said  to  train  memory,  whether  training  in  learning  one 
sort  of  material  or  under  one  set  of  conditions  is  trans- 
ferred to  learning  some  other  material  or  under  another  set 
of  conditions.  All  experiments  in  learning  under  experi- 
mental conditions  show  important  improvement  with  prac- 
tice. There  is  also  some  improvement  when  one  practises 
on  nonsense  syllables  and  tests  by  the  capacity  to  learn 
sense  material  or  by  any  form  of  rote  learning.  It  has 
sometimes  been  held  that  memory  was  something  that 
could  be  trained  in  and  of  itself  hke  a  muscle.  Practically 
all  modern  evidence  favors  the  view  that  the  improvement 
is  really  in  the  methods  that  are  used  in  learning.  One  be- 
comes accustomed  to  attending  under  the  peculiar  condi- 
tions of  the  laboratory;  one  forms,  consciously  or  uncon- 
sciously, good  habits  of  study,  learns  to  read  with  the 
intention  of  remembering,  and  these  factors  may  be  car- 
ried over  to  any  other  material  with  advantage.  From 
what  we  know,  this  is  the  only  sense  in  which  memory  can 
be  improved  in  any  general  fundamental  way,  and  this  is 
sufficient  to  account  for  the  improvement  actually  demon- 
strated. Another  form  of  improvement  can  be  noticed  in 
connection  with  sense  material,  a  form  that  comes  without 


4o6        FUNDAMENTALS   OF  PSYCHOLOGY 

effort  and  is  a  necessary  part  of  all  learning.  This  is  the 
increase  in  ability  to  understand,  which  develops  with  in- 
creased knowledge.  As  knowledge  accumulates  and  is  well 
ordered,  more  points  of  reference  develop  and  each  of  these 
serves  as  a  peg  upon  which  new  facts  may  be  hung.  Just 
as  Dr.  Riickle's  new  numbers  could  be  referred  to  numbers 
known  as  the  squares  and  cubes  of  small  numbers,  and 
could  be  remembered  in  terms  of  those,  so  a  new  fact  that 
can  be  given  a  place  in  the  system  of  knowledge,  as  an  in- 
stance of  a  familiar  principle,  is  readily  remembered.  This 
system  of  knowledge  grows  with  learning,  and  as  each  ad- 
dition to  it  is  preparation  for  new  acquirement,  all  learn- 
ing may  be  said  in  this  sense  to  train  the  memory. 

REFERENCES 

Colvin:  The  Learning  Process. 
Meumann:  The  Psychology  of  Learning. 

MiJLLER,  G.  E.:   Gedachtnisstatigskeit.     Zeitschrift  f.  Psychol- 
ogic, Erganzungsbde.    V,  VIII,  IX. 


CHAPTER  XIII 
REASONING 

Closely  related  to  memory  is  reasoning.  Two  processes 
are  ordinarily  included  under  reasoning.  The  first  is  the 
construction  in  idea  of  plans  and  machines  that  may 
later  be  apphed  to  actual  practice  and  built  of  real  material 
instead  of  in  idea.  The  second  is  a  process  of  understand- 
ing and  explaining  natural  events  and  phenomena. 

Reasoning  as  Planning.  —  In  the  first  case  we  have  a 
desire  or  need  which  must  be  satisfied  or  supplied  and  for 
which  none  of  the  objects  which  are  immediately  seen  or 
can  be  remembered  will  suffice.  This  is  the  process  which 
is  typical  of  invention  and  discovery,  of  planning  and  de- 
signing. The  thought  constructions  save  the  time  and 
materials  which  might  be  wasted  in  hit  or  miss  trial.  When 
a  house  is  to  be  built,  it  is  first  thought  through  in  detail 
or  drawn  with  the  different  spaces  allotted  as  they  should 
be  and  the  difTerent  materials  decided  upon.  Then  when 
the  actual  construction  begins  many  at  least  of  the  different 
problems  are  settled.  The  other  unforeseen  difficulties 
that  appear  in  the  adjustment  of  various  details  are  also 
first  settled  in  thought. 

Reasoning  as  Understanding.  —  The  second  type  of 
reasoning  is  typical  of  the  attempts  to  understand  natural 
phenomena  or  other  events.  It  aims  not  at  changing  the 
course  of  the  world  directly,  but  at  seeing  why  it  works  as 
it  does.  Of  course  ultimately  this  understanding  of  the 
processes  of  the  universe  may  enable  us  to  change  them 
407 


4o8        FUNDAMENTALS   OF  PSYCHOLOGY 

in  order  better  to  comply  with  our  needs.  The  process  of 
reasoning  with  the  end  of  understanding  is  typical  of 
science.  The  immediate  ends  of  science  are  to  understand. 
The  two  processes  of  reasoning  are  much  ahke  in  the  in- 
centives which  induce  them  and  in  the  method  which  is 
used.    Still  it  is  well  to  recognize  them  as  distinct. 

Reasoning  always  Arises  from  a  Thwarting  of  Progress. 
—  Both  forms  of  reasoning  are  occasioned  by  the  feeUng 
of  need  of  change  in  a  present  condition.  In  the  more  active 
type  —  that  of  planning  —  we  feel  that  the  present  situa- 
tion leaves  something  to  be  desired,  and  by  reasoning  we 
attempt  to  find  a  means  of  supplying  that  lack.  In  the 
second  type  —  that  of  understanding  —  we  feel  puzzled 
over  some  occurrence  that  does  not  seem  to  run  in  the 
regular  course,  and  we  seek  an  explanation.  Both  may  be 
said  to  arise  from  a  thwarted  purpose.  In  the  first  the 
thwarting  comes  from  an  inability  to  attain  a  desired  end; 
in  the  second  there  is  a  failure  to  see  why  the  particular 
event  runs  as  it  does.  As  an  illustration  of  the  first  we  may 
take  the  need  of  making  a  balky  automobile  go ;  of  the  second 
type,  an  inability  to  understand  why  the  sun  rises  in 
the  north  in  the  summer  while  we  have  always  been  told 
that  it  rises  in  the  east.  In  both  cases  problems  may  present 
themselves  as  vague  complexes,  as  mere  feehng  that  some- 
thing is  lacking  and  must  be  suppHed.  The  initial  active 
step  in  either  case  is  to  become  definitely  aware  of  exactly 
what  is  wrong.  This  is  known  as  the  process  of  judging.  It 
consists,  in  either  form  of  reasoning,  in  referring  the  felt 
need  or  the  observed  fact  to  a  definite  name  and  group  of 
phenomena.  To  understand  why  the  car  stops  it  is  neces- 
sary to  examine  part  by  part  in  the  light  of  a  knowledge  of 
the  machine  or  of  experiences  with  other  machines  which 
have  stopped  in  the  past.    The  particular  difficulty  may  be 


REASONING  409 

discovered  upon  examination  to  be  due  to  a  broken  wire 
in  the  ignition  system.  This  constitutes  a  reference  of  the 
vague  general  fact  that  the  automobile  has  stopped  to  a 
defined  class  of  reasons  why  it  should  stop.  Similarly,  the 
fact  that  the  sun  rises  out  of  place  or  that  it  shines  into  a 
north  window  early  in  the  morning  leads  to  an  appreciation 
of  the  general  fact  that  it  does  rise  far  north  in  the  summer 
and  that  this  needs  explanation. 

The  Active  Steps  in  Reasoning.  —  In  each  case,  after 
the  phenomenon  has  been  discovered  or  exphcitly  indi- 
cated, the  active  process  of  reasoning  begins.  The  first 
step,  when  reasoning  is  viewed  as  planning,  is  to  find  some 
way  of  remedying  the  situation.  This  is  always  the  longest 
and  in  many  ways  the  most  important  operation.  It  con- 
sists in  casting  about  until  some  idea  occurs  that  will 
promise  to  supply  the  defect.  After  an  idea  has  presented 
itself  as  to  how  the  result  may  be  achieved  it  is  still  neces- 
sary to  convince  one's  self  and  often  to  convince  others 
that  the  suggestion  is  correct,  and  that  if  put  into  apphca- 
tion  it  would  produce  the  change  desired.  This  is  the 
process  of  proof,  and  is  the  process  that  has  always  at- 
tracted most  attention.  It  is  the  process  that  the  logician 
identified  with  reason,  although  it  is  the  one  that  is  least 
active,  and  in  many  ways  the  least  important.  Reasoning, 
as  we  have  said,  always  arises  from  a  thwarted  purpose, 
or  felt  need.  The  first  stage,  after  this  need  is  felt,  is  to 
analyze  this  need,  to  discover  clearly  what  is  wrong;  this 
is  judgment.  Then  one  must  find  a  solution;  this  is  infer- 
ence. Finally  it  is  necessary  to  show  that  it  is  actually 
a  solution;    this  is  proof. 

These  various  processes  involve  many  of  the  association 
and  other  mental  processes  which  have  already  been  con- 
sidered.    In  addition  there  are  three  fundamental  facts 


4IO        FUNDAMENTALS   OF  PSYCHOLOGY 

or  phases  that  have  not  been  fully  considered  which  are 
involved  at  each  stage  of  reasoning,  which  we  must  dis- 
cuss here  in  detail.  These  are  meaning,  the  concept,  and 
behef.  Meaning  is  important,  since  almost  all  thinking  is 
in  symbols,  in  language,  or  in  ideas,  that  mean  something 
different  from  what  they  are  in  themselves.  The  concept 
is  closely  related  to  meaning,  since  most  of  the  processes 
that  carry  the  meanings  are  concepts.  Belief  is  important 
as  a  preliminary  or  substitute  for  proof  in  the  acceptance 
of  a  solution,  once  it  has  been  reached  or  has  been  sug- 
gested. These  terms  we  may  define  and  discuss  as  a  pre- 
liminary to  solving  the  problems  themselves. 

Meaning 

Meaning  and  the  Concept.  —  Meaning  and  the  concept 
are  in  large  measure  correlative  terms,  as  neither  would  have 
any  significance  in  psychology  were  it  not  for  the  other. 
In  its  earliest  form,  meaning  is  the  fact  that  one  bit  of  men- 
tal content  represents  or  stands  for  something  else.  A 
word  stands  for  an  object  in  our  thought  and  may  be  used 
in  its  place  in  all  of  our  thinking  about  that  object.  Mean- 
ing tends  to  become  something  almost  as  definite  as  the 
object  itself.  At  least  it  becomes  a  mental  characteristic 
of  the  object  and  a  felt  addition  to  the  mental  state,  which 
is  almost  as  important  as,  at  times  even  more  important 
than,  the  mental  state  itself.  A  picture  or  image  of  a  more 
concrete  type  may  also  take  on  meaning,  and  come  to 
represent  a  number  of  other  images  or  objects  as  well  as 
itself.  In  fact  every  mental  state  may  be  said  to  have 
meaning,  in  that  it  stands  for  something  in  addition  to 
itself,  and  is  important  to  us  for  what  it  means  rather  than 
for  itself.  This  is  the  same  condition  which  we  found  in 
perception,  in  that  a  sensation  of  one  kind  represents  some- 


MEANING  411 

thing  else  and  that  something  else  really  replaces  it  in  our 
thought.  We  saw  that  a  strain  sensation  represents  a 
certain  distance,  and  that  when  there  is  a  certain  strain 
in  the  eye-muscles  we  think  of  that  distance  although  we  do 
not  become  aware  of  the  strain  itself.  A  figure  drawn  with 
obtuse  and  acute  angles  represents  a  square  figure  in  another 
plane  of  space;  and  we  see  that  square  figure,  although 
we  do  not  notice  the  angles  that  induce  us  to  make  the 
inference.  All  these  may  be  regarded  as  instances  of  mean- 
ing or  representation  in  perception.  In  each  case  a  sensa- 
tion or  group  of  sensations  represents  or  stands  for  some- 
thing else;  and  in  each  case  we  become  aware  of  what  the 
sensations  represent,  not  of  the  sensations  that  are  actually 
given. 

The  Nature  of  Meaning.  —  How  one  idea  can  thus 
stand  for  another  needs  to  be  examined  more  closely. 
A  study  of  the  conditions  under  which  meaning  originates 
indicates  that  it  is  at  first  a  mere  process  of  association  or 
connection  through  contiguity.  One  idea  tends  to  suggest 
the  other  because  it  has  been  seen  at  the  same  time  with 
it.  A  man's  name  serves  at  first  to  recall  the  picture  of  the 
man;  then  it  is  used  in  place  of  the  picture,  because  we  are 
certain  that  the  mental  picture  may  be  aroused  at  any  time 
that  we  desire  to  recall  it,  and  we  are  satisfied  with  that 
feeling.  Soon  it  also  becomes  associated  with  the  capacities 
and  activities  of  that  man,  and  may  serve  quite  as  fully 
to  represent  hun  in  thought  as  would  the  image  itself. 
In  fact,  it  often  seems  to  be  a  more  satisfactory  representa- 
tive of  his  capacities  and  other  more  active  and  vital 
aspects  of  him  than  is  the  mental  picture  of  him.  It  has 
been  more  often  and  more  closely  associated  with  him  than 
has  the  picture,  and  so  when  we  think  of  those  aspects  we 
may  be  more  likely  to  recall  the  name  than  the  image. 


412        FUNDAMENTALS   OF  PSYCHOLOGY 

This  may  be  true  especially  of  men  whom  we  know  through 
their  writings  or  from  reputation,  rather  than  through  their 
actual  presence.  In  such  cases,  when  the  man  is  seen  for  the 
first  time  one  may  find  one's  self  harking  back  in  thought 
to  the  name,  to  find  one's  self  saying  in  surprise,  this  is 
Ribot.  The  name  in  such  cases  gives  meaning  to  the  image. 
These  associates  cluster  about  the  word  and  seem  in 
many  cases  to  give  an  entirely  different  feeling  to  the  word 
from  that  which  it  would  have  without  them.  Probably 
a  large  part  of  any  experience  depends  upon  these  asso- 
ciates. As  in  recognition,  it  seems  that  the  associates  are 
frequently  aroused  in  slight  degree  when  they  are  not  suf- 
ficiently active  to  give  a  direct  awareness  of  their  presence. 
Thus  a  word  with  one  group  of  associates  will  seem  to  be 
different  from  the  same  word  with  another  group,  although 
the  associates  themselves  may  not  be  definitely  in  mind. 
The  meaning  changes  as  the  partially  aroused  associates 
vary.  These  vary  under  the  influence  of  the  mental  con- 
text or  attitude,  as  was  seen  in  Chapter  VI.  This  makes 
possible  the  use  of  the  same  word  or  sound  for  entirely 
different  objects  and  ideas.  Such  a  word  as  bar  has  a  num- 
ber of  altogether  different  meanings,  and  they  seldom 
interfere  with  each  other.  If  one  thinks  of  an  attorney, 
it  has  an  entirely  different  meaning  from  that  which  it  has 
as  one  thinks  of  a  harbor,  or  of  carpentry,  or  of  a  beverage. 
In  each  of  these  cases  we  may  think  of  the  word  as  a  centre 
of  associates  which  spring  up  as  it  enters  consciousness. 
One  group  will  come  when  the  mind  is  in  one  attitude, 
and  another  is  aroused  when  the  mind  is  in  a  different  atti- 
tude. Even  when  the  associates  are  not  definitely  in  mind, 
the  meaning  will  be  different  under  different  conditions; 
this  meaning,  we  may  assume,  is  due  to  the  different  par- 
tially aroused  associates. 


MEANING  413 

Meaning  as  Conscious  Process.  —  In  order  to  see  clearly 
that  there  is  a  definite  conscious  process  of  meaning,  we 
may  artificially  eliminate  the  meaning.  This  can  be  done, 
according  to  Professor  James,  by  staring  for  a  few  mo- 
ments at  a  word  in  isolation.  As  one  continues  to  hold 
the  word  in  mind,  it  seems  to  become  a  mere  group  of  letters, 
without  any  of  the  meaning  that  it  has  as  one  looks  at  it 
casually,  or  even  any  of  the  meaning  that  was  present  when 
the  staring  began.  The  '  feeling  '  of  the  word  is  altogether 
different.  One  may  believe  that  the  associations,  that  were 
aroused  at  first,  cease  to  be  active  during  the  long-drawn- 
out  staring,  and  so  meaning  with  its  characteristic  quality 
disappears.  In  general  it  seems  that  much  of  the  con- 
sciousness that  is  aroused  by  the  ideas  that  we  have  is 
due  to  meaning.  We  seldom  if  ever  entirely  dissociate  a 
sensation  or  memory  from  its  meaning,  and  much  that  we 
ascribe  to  the  bare  element  is  really  due  to  the  associates 
that  it  arouses.  When  we  do  by  artifice  divorce  a  sensation 
or  memory  element  from  its  meaning,  we  are  surprised  to 
discover  what  it  is.  This  is  probably  another  effect  of  the 
doctrine  frequently  emphasized  throughout,  that  nothing 
comes  to  mind  alone;  or,  in  nervous  terms,  that  an  element 
never  acts  in  isolation. 

Meaning  Present  when  Associates  are  not  Noticed.  — 
It  should  be  added  that,  even  if  we  accept  the  assumption 
made  above  —  that  meaning  is  due  to  the  awakening  of 
old  association  paths  —  nevertheless,  meaning  persists 
when  we  are  no  longer  aware  of  the  associates  themselves. 
This  was  seen  to  be  true  of  recognition  as  well;  and  recogni- 
tion, we  showed,  was  due  to  a  similar  complete  or  partial 
arousitig  of  associations.  The  matter  may  go  even  farther, 
in  that  meaning  may  be  present  when  we  are  not  even 
aware  of  the  sensation  or  image  that  gives  rise  to  the 


414        FUNDAMENTALS   OF  PSYCHOLOGY 

meaning.  One  is  occasionally  aware  of  meaning  something, 
as  when  one  intends  to  discuss  a  topic,  although  no  words 
or  other  images  are  present,  or  are  at  least  not  distinct. 
This  has  led  Kiilpe  and  others  of  his  school  and  Wood- 
worth  to  assert  that  meaning  may  be  a  new  form  of  con- 
sciousness, independent  of  all  imagery.  That  one  may 
think  in  meanings  alone  is  what  they  call  '  imageless 
thought.'  Whether  these  cases  are  more  than  the  final 
stage  in  the  dropping  out  of  associates,  which  are  at  first 
present,  has  been  questioned.  Certain  it  is  that  we  find 
many  cases  in  perception  in  which  the  sensation  is  not 
noticed  in  itself  but  only  for  the  meaning  that  it  carries. 
Strain  sensations  about  the  eyes  are  not  noticed,  but 
nevertheless  they  mean  distance,  and  through  this  mean- 
ing we  perceive  distance.  Similarly  one  is  not  aware  of 
the  sensations  in  reading,  but  only  of  the  words  seen  or  of 
their  meaning.  In  recognition,  we  noticed  that  one  might 
have  a  vague  feehng  of  famiKarity  when  the  object  that 
induced  the  feehng  was  not  definitely  in  consciousness. 
All  these  instances  are  similar  to  the  case  of  meaning  where 
there  is  no  image  to  bear  or  suggest  it.  It  should  in  fairness 
be  added  that  the  holders  of  the  theory  that  meaning  is  a 
new  and  pecuHar  form  of  consciousness  are  not  convinced  by 
this  criticism.  They  insist  that  these  are  all  cases  in  which 
the  new  element  is  the  determining  factor  in  consciousness, 
and  think  it  needs  no  explanation. 

Concepts 

The  Concept.  —  The  fact  that  all  ideas  have  an  impor- 
tance only  from  their  connections,  and  that  all  are  really 
representative  of  something  else,  leads  naturally  to  an 
explanation  of  the  concept.  Historically,  the  concept  is 
the  element  or  an  element  which  is  important  only  as  it 


CONCEPTS 


415 


represents  something  else.  In  general,  it  is  defined  as  a 
mental  process  that  represents  general  or  abstract  ideas 
rather  than  particulars.  In  the  beginning  we  may  regard 
the  concept  as  representative  of  several  different  objects 
rather  than  of  one  alone.  In  this  sense  all  common  nouns 
are  concepts.  They  represent  all  objects  of  a  class  in- 
dififerently.  This  notion  of  the  concept  offers  no  difficulty 
if  we  remember  that  all  ideas  are  similarly  representative. 
They  all  have  meanings  that  reach  beyond  themselves. 
Each  word  or  object  has  many  associates,  similar  in  some 
degree,  which  have  been  added  from  time  to  time.  The  one 
word  representing  the  object  is  capable  of  recalHng  all  of 
the  group  of  associates,  and  stands  for  the  members  of  the 
group  because  of  the  partial  arousal  of  the  associates,  even 
when  the  whole  group  is  not  definitely  or  completely 
aroused.  One  has  the  feehng  that  one  might  recall  them 
even  when  they  are  not  actually  recalled,  and  this  feehng 
or  a  partial  arousal  gives  the  experience  that  we  call  the 
meaning  of  the  word. 

Concepts  Represent  Abstract  Qualities.  —  Concepts 
represent  qualities  as  well  as  objects.  In  many  cases  the 
qualities  which  are  represented  may  be  regarded  as  the 
characteristics  of  the  objects  that  render  them  sufficiently 
alike  to  be  grouped  in  a  single  class.  In  the  recognition  of 
animals  as  a  class,  it  is  the  mass  of  quahties  that  we  call 
hfe  that  makes  possible  the  grouping.  We  may  become 
aware  of  these  characteristics  individually  and  give  a 
name  to  each.  This  form  of  the  concept  —  referring  to 
a  quahty  —  is  quite  as  frequent  as  the  concept  which 
merely  represents  a  class,  and  in  many  ways  it  is  more 
important.  After  the  members  of  a  class  have  become 
connected  through  the  possession  of  some  one  important 
quahty  or  aspect,  that  aspect  is  selected,  given  an  inde- 


4i6        FUNDAMENTALS   OF  PSYCHOLOGY 

pendent  name,  and  comes  to  stand  in  thought  as  a  real 
entity.  In  many  cases  the  scientist  estabhshes  the  in- 
dependent existence  of  what  at  first  was  merely  a  mark  or 
characteristic  of  a  class.  Such  are  the  physical  concepts 
of  heat,  force,  electricity,  and  magnetism,  to  mention 
only  a  few.  How  far  these  would  be  said  to  have  real 
independent  existence,  and  how  far  they  are  characteristics 
of  a  group,  is  a  question  which  not  all  would  answer  alike. 
Certainly  they  are  not  merely  class  concepts;  and,  equally 
clearly,  without  them  a  large  part  of  modern  thinking  and 
investigation  would  be  much  less  effective  than  it  is. 

Concept  as  Type.  —  Closely  related  to  this  form  of  the 
concept,  which  represents  something  abstracted  from  the 
particular  ideas  or  experiences,  is  the  sense  in  which  the 
term  concept  is  used  as  the  quality  that  is  represented  by 
the  general  idea  rather  than  as  the  mental  state  that 
represents  it.  Thus,  force,  for  example,  is  something  which 
is  never  actually  experienced  in  the  form  in  which  we  tliink 
of  it.  It  is  an  abstraction  which  we  must  use  if  we  are  to 
appreciate  the  physical  universe  clearly,  and  which  is 
warranted  by  the  fact  that  it  is  a  necessity  for  clear  think- 
ing. In  this  sense  all  knowledge  is  made  up  of  concepts. 
The  particulars  are  the  raw  materials  from  which  the  fully 
unified  system  is  built.  One  may  picture  the  system  of 
knowledge  as  made  up  of  various  elements  that  have  been 
fitted  together  to  constitute  a  consistent  whole.  These 
elements  are  for  the  most  part  not  given  immediately  in 
sensation,  but  are  the  results  of  various  refinements,  of 
various  ways  of  working  over  the  raw  materials,  until 
some  order  is  brought  into  the  originally  inchoate  mass. 
We  have  seen  the  process  at  work  even  in  perception. 
As  was  pointed  out  there  on  several  occasions,  what  is 
perceived  is  not  merely  a  mass  of  sensations,  nor  is  it  a 


CONCEPTS  417 

single  sensation  that  suggests  some  other  single  sensation 
or  group  of  sensations;  it  is  a  type,  an  organized  product 
of  many  experiences  which  have  finally  given  rise  to  a 
construct  consistent  with  all  of  our  different  related  ex- 
periences. This  it  is  that  is  in  mind  when  a  single  stimulus 
presents  itself.  Thus,  to  repeat  our  simple  instance,  we 
see  the  top  of  a  table  as  square,  not  because  it  is  square 
on  the  retina,  nor  because  we  have  seen  it  more  frequently 
under  conditions  that  make  it  appear  square  than  when 
distorted  by  perspective,  • —  probably  it  never  has  been 
seen  undistorted,  —  but  because  a-11  that  we  know  about 
the  table  top  harmonizes  with  the  assumption  that  it  is 
square.  When  tested  or  measured  it  proves  to  be  square; 
a  similar  surface  must  be  made  with  right  angles,  it  fits 
into  square  corners.  It  is  believed  to  be  square  because 
that  assumption  fits  in  with  all  of  our  other  experiences. 

Development  of  Concepts.  —  It  is  by  this  method  that 
most  of  the  notions  of  external  objects  develop.  Position 
is  a  notion  that  cannot  be  referred  to  any  single  experience. 
Depth  also  cannot  be  said  to  be  merely  the  sensation  of  the 
motion  necessary  to  reach  the  object,  but  is  rather  a  con- 
cept or  type  developed  through  many  tests,  and  accepted 
because  it  harmonizes  or  orders  many  different  experiences. 
Space  in  general  is  a  similar  type.  If  we  turn  from  per- 
ception to  less  objective  things,  the  same  principle  may  be 
applied.  The  development  of  the  number  concept  can  be 
followed  among  the  different  primitive  nations.  In  northern 
Borneo,  the  natives  still  have  no  developed  notion  of 
number  apart  from  objects.  When  counting  they  use  the 
fingers  and  toes;  and  when  the  number  rises  above  twenty, 
another  man  is  called  and  the  objects  are  checked  against 
his  fingers  and  toes.  The  remnants  of  this  counting  can 
easily  be  traced  in  the  decimal  system  and  in  the  score. 


41 8        FUNDAMENTALS   OF  PSYCHOLOGY 

In  this  instance  the  concept  carries  with  it  more  of  the 
original  sensory  material  from  which  it  develops  than  do 
space  and  position,  but  in  the  course  of  time  the  separation 
from  the  concrete  is  complete;  and,  for  us,  number  carries 
with  it  practically  no  implication  of  fingers  and  toes  except 
for  the  use  of  a  few  words,  such  as  digits. 

Concepts  Alone  in  the  Chinese  Written  Language.  —  Very 
important  as  evidence  both  of  the  way  the  concept  devel- 
ops and  also  of  the  relative  independence  of  the  concept 
when  developed  is  the  written  Chinese  language.  Instead 
of  representing  sounds  as  do  the  characters  in  the  occiden- 
tal languages,  the  Chinese  characters  represent  ideas.  In 
consequence,  two  peoples  Hke  the  Chinese  and  the  Japa- 
nese, with  altogether  different  spoken  tongues,  may  use  the 
same  written  language.  The  symbols  in  Chinese  were 
originally  representative  of  objects;  but,  with  time,  con- 
venience in  writing  has  changed  them  so  that  in  many 
cases  there  is  Httle  similarity  between  the  object  and  its 
symbol.  Very  instructive  evidence  of  the  nature  of  ab- 
straction is  the  way  more  general  ideas  are  represented. 
Thus  morning  is  represented  by  the  sun  near  the  horizon; 
evening  by  the  bird  on  its  nest.  Good  is  represented  by 
the  symbol  of  a  woman  and  a  child  together.  Less  gallant 
is  the  symbol  for  treachery,  which  is  three  women  together; 
and  for  strife  or  dissension-,  which  is  two  women  under  one 
roof.  In  general  it  will  be  seen  that  sen  object  which  is  a 
frequent  accompaniment  of  a  general  idea  comes  to  repre- 
sent that  idea.  Interesting,  too,  it  is  to  note  that  the  orig- 
inal meaning  of  the  symbols  are  usually  not  thought  of, 
when  used  for  these  secondary  representations  of  abstract 
ideas. 

Knowledge  a  System  of  Concepts.  —  Leaving  out  of 
consideration  for  the  moment  the  question  of  how  the  con- 


CONCEPTS  419 

cepts  develop,  it  is  evident  that  organized  knowledge  con- 
sists in  its  entirety  of  a  system  of  concepts.  When  any- 
thing can  be  referred  to  a  concept,  we  place  it,  we  can  use 
it,  we  understand.  On  the  other  hand,  when  it  is  possible 
to  develop  a  notion  or  concept  that  will  organize  a  group 
of  facts,  we  accept  the  concept  as  true,  and  use  it  until 
some  new  facts  appear  that  are  out  of  harmony  with  it, 
when  that  concept  is  given  up  and  another  substituted  for 
it.  Just  as  in  the  perception  of  space,  the  concept  or  type 
is  assumed  to  be  real  and  all  else  is  adjusted  to  it,  so  in 
science  or  philosophy  or  in  everyday  hfe  the  concepts  are 
accepted  as  the  reals,  other  experiences  are  merely  ap- 
pearance. The  systems  of  concepts  are  by  no  means  con- 
sistent with  each  other,  but  must  be  consistent  within 
themselves.  Thus,  if  one  consider  the  experience  of  per- 
ceiving the  table  from  the  standpoint  of  the  concepts  of 
the  different  sciences,  we  would  be  told,  on  the  one  hand, 
that  it  was  nothing  but  a  mass  of  atoms  of  hydrogen  and 
carbon  and  oxygen  in  different  arrangements  with  a  few 
odd  elements  thrown  in;  that  its  peculiar  character  de- 
pended upon  the  way  the  atoms  were  grouped  in  the  mole- 
cules. For  the  chemist  it  is  this  and  nothing  more.  For 
the  physicist  the  picture  changes.  Atoms  withdraw  to  the 
background,  and  forces  come  to  the  front.  Gravitational 
attraction  keeps  it  in  place  on  the  earth,  and  gives  it  weight. 
We  see  the  table  as  a  result  of  the  vibrations  in  the  ether 
which  it  reflects;  and  its  color  is  determined  by  the  rays 
that  it  absorbs  and  reflects.  If  one  happens  to  be  talking 
to  a  physicist  of  the  latest  school,  electric  waves  are  sub- 
stituted for  the  vibrations  of  the  ether.  In  any  case,  ex- 
planation is  in  terms  of  a  system  of  concepts,  however  the 
concepts  may  differ.  The  physiologist  finds  his  explana- 
tion of  the  experience  in  the  nervous  structure  of  the  eye, 


420        FUNDAMENTALS   OF  PSYCHOLOGY 

in  photo-chemical  processes  in  the  rods  and  cones,  in  the 
excitations  and  responses  of  the  neurones.  The  psycholo- 
gist finds  the  explanation  in  a  group  of  sensations  of  strain, 
of  light  and  shade,  of  images.  These  are  the  types  or  con- 
cepts to  which  experience  is  referred,  as  the  psychologist 
attempts  to  understand  it.  In  short,  our  simple  experience 
has  been  dissolved  in  a  great  many  different  ways,  no  one 
of  which  leaves  anything  of  the  original  experience;  and 
yet  without  this  dissolution  into  concepts,  it  could  not  be 
understood. 

No  Understanding  Without  Concepts.  —  Without  con- 
cepts all  would  be  confusion.  This  is  clear  from  a  study  of 
the  early  languages  and  the  lower  forms  of  human  thought. 
It  is  asserted  that  among  the  lower  South  African  tribes 
there  is  no  notion  of  direction  in  the  absolute  sense.  The 
individual  gropes  his  way  from  place  to  place  by  memory 
of  each  landmark  along  the  way,  and  has  no  idea  in  which 
direction  he  is  going.  He  cannot  keep  his  bearing  even 
with  reference  to  the  rising  or  the  setting  sun.  How  con- 
fused his  notion  of  the  world  must  be,  can  easily  be  appre- 
ciated. Similarly,  where  numbers  are  restricted  to  a  score, 
where  length  can  be  measured  only  in  paces,  or  in  days' 
journeys,  and  other  concepts  are  equally  faulty  or  alto- 
gether lacking,  all  thought  must  be  decidedly  vague  and 
uncertain.  Even  the  use  of  purely  personal  concepts  of 
force,  as  in  the  explanation  of  the  winds  and  other  natural 
phenomena  by  spirits,  and  the  generally  accepted  anthro- 
pomorphic explanation  of  events  and  causes,  means  that 
little  progress  can  be  made  toward  accurate  understanding 
or  use  of  natural  forces.  Adequacy  of  concepts  means  ade- 
quacy of  understanding,  and  that  in  turn  means  successful 
action  and  appHcation  of  means  to  ends.  What  experience 
would  be  hke  without  concepts  one  cannot  appreciate.    It 


CONCEPTS  421 

would  be  of  course  a  hopeless  confusion,  like  waking  from 
a  bad  dream  into  an  entirely  new  environment.  Nothing 
would  be  clear,  nothing  would  be  definite.  To  all  intents 
and  purposes,  without  concepts  there  would  be  no  con- 
sciousness. Adequate  concepts  are  the  handmaidens  of 
adequate  thought. 

Concepts  Develop  by  Trial  and  Error.  —  The  problem 
of  the  origin  of  concepts  as  the  elements  of  understanding 
has  been  one  of  the  persistent  problems  of  philosophy.  We 
find  that  the  general  theories  divide  themselves,  like  the 
theories  of  space,  into  those  which  assume  concepts  and 
regard  them  as  determining  the  course  of  development  of 
knowledge,  and  those  which  would  develop  the  concepts 
themselves  from  and  through  experience.  Plato,  for  ex- 
ample, has  in  his  ideas  a  system  of  concepts  that  are  in- 
nate, the  representatives  in  man  of  the  eternal  verities, 
through  which  all  experience  obtains  what  truth  it  may 
have.  On  the  other  hand,  we  have  more  empirical  the- 
ories that  would  derive  concepts  from  the  experience  of 
the  individual.  They  regard  the  more  abstract  concepts  as 
developed  on  the  basis  of  individual  suggestions  worked 
over  and  modified  to  harmonize  the  experience  of  the  race. 
This  is  essentially  the  suggestion  that  was  made  with  ref- 
erence to  the  types  in  perception.  They  may  be  in  part  or 
at  times  derived  by  the  accumulation  of  particular  experi- 
ences that  have  been  consolidated  or  modified  by  use. 
Very  largely  and  in  many  cases,  however,  they  seem  to  re- 
sult from  hitting  by  chance  upon  some  construction  that 
harmonizes  with  the  experiences.  When  a  construction  is 
found  that  meets  this  test,  it  is  accepted.  Certain  it  is 
that  concepts  are  modified  with  the  passage  of  time  and 
the  growth  of  knowledge,  and  it  is  just  as  certain  that  a 
concept  is  seldom  the  direct  product  of  the  action  of  the 


42  2        FUNDAMENTALS   OF  PSYCHOLOGY 

senses.  In  the  formation  of  laws,  experimental  science 
shows  a  tendency  to  consohdate  particular  observations 
into  generalizations.  Li  this  consohdation,  trial  and  error 
are  important  factors.  However  derived,  we  insist  that 
our  knowledge,  as  used  in  thought  and  developed  through 
perception,  becomes  largely  a  system  of  concepts,  of  types, 
and  that  these  serve  to  explain  the  concrete,  and  in  many 
cases  in  themselves  to  constitute  the  concrete.  Without 
concepts  knowledge  would  be  no  knowledge  but  a  mere 
mass  of  confusion. 

Concept  as  Representative  Idea  and  as  Type.  —  Two 
forms  of  the  concept  may  accordingly  be  distinguished. 
The  first  is  a  definite  mental  state  that  means  a  number 
of  particulars  or  a  number  of  general  qualities  of  any  sort. 
This  takes  the  form  of  a  word,  a  typical  group  of  sensa- 
tions; or  it  may  be  reduced  to  nothing  or  very  nearly 
nothing  but  the  meaning,  the  reference  itself.  The  second 
form  is  an  organized  idea,  a  type  that  has  been  proved  by 
tests  to  satisfy  many  experiences,  and  in  consequence  is 
accepted  as  real.  It  is  this  concept  that  is  usually  meant. 
It  is  what  we  accept  as  the  external  object  of  common 
sense,  it  is  the  fundamental  structure  or  force  or  principle 
of  explanation  in  natural  science,  or  in  psychology.  In 
many  cases  these  types,  too,  are  not  absolutely  clearly  pic- 
tured but  are  represented  in  consciousness  in  some  sche- 
matic fashion.  At  other  times,  as  in  perception,  the  types 
constitute  the  clearest  and  most  definite  structures  of  con- 
sciousness. They  are  consciousness,  and  all  else  is  subor- 
dinated to  them.  In  every  case  they  are  all  that  we  are 
really  conscious  of  at  the  moment,  whether  they  be  merely 
meant,  or  actually  reproduced  in  all  their  clearness. 

The  Stages  of  Active  Reasoning.  —  At  every  stage  in 
active  reasoning,  use  is  made  both  of  meaning  and  of  the 


CONCEPTS  423 

concept.  Reasoning  has  as  its  object  either  bringing  order 
into  experience  or  discovering  ways  of  improving  the  en- 
vironment, and  justifying  suggestions  for  new  advances. 
In  both  cases,  reference  to  the  established  system  of  knowl- 
edge, to  concepts  and  generally  accepted  laws,  plays  a 
prominent  part.  Practically  all  reasoning  operations  deal 
with  real  things  or  their  symbols.  Each  of  the  four 
processes  into  which  reasoning  was  divided  makes  use  of 
concepts. 

The  reasoning  process  is  initiated  by  the  lack  of  a 
satisfactory  concept  or  the  need  for  the  solution  of 
some  difficulty. 

In  the  solution  of  a  problem  or  in  obviating  a  diffi- 
culty, the  judgment  consists  merely  in  referring  the 
difficulty  to  a  concept.  One  is  prepared  to  start  on 
the  solution  when  one  appreciates  what  the  difficulty 
is,  which  involves  assigning  it  to  a  known  class  or  a 
clear  idea. 

The  inference,  or  problem  of  finding  a  solution,  in- 
volves concepts  only  in  that  it  is  customary  to  try  one 
after  another  of  the  familiar  concepts  to  see  if  they  fit. 
Where  an  old  concept  is  used,  it  is  used  in  a  new 
connection  if  the  reasoning  is  real,  and  the  solution 
original. 

In  the  final  stage,  proof,  a  concept  or  old  organized 
experience  is  the  factor  that  induces  belief.  It  is  only 
as  one  can  refer  the  suggested  solution  to  some  system 
of  organized  knowledge,  to  a  concept  or  system  of 
concepts,  that  conviction  of  the  truth  will  be  induced. 
As  we  shall  see  in  detail  in  each  stage,  reasoning  in 
all  of  its  parts  is  possible  only  through  the  use  of  a 
developed  series  of  concepts. 


424        FUNDAMENTALS   OF  PSYCHOLOGY 

The  Initiation  of  the  Reasoning  Process 

The  Initiation  of  the  Reasoning  Process.  —  Reasoning 
as  a  whole  must  have  a  positive  stimulus.  The  problem  is 
always  forced  upon  the  individual  by  some  inadequacy 
of  old  habits  or  of  old  thoughts,  by  something  that  goes 
wrong  in  the  ordinary  routine.  Where  habit  and  routine 
suffice,  one  never  reasons.  Necessity  is  the  mother  of  all 
thought,  as  of  all  invention.  Reasoning  results  when  a 
man  is  thwarted  in  his  mental  or  physical  progress.  On 
the  mental  side  some  fact  presents  itself  that  will  not  fit 
into  the  theories  already  developed.  The  number  of  spe- 
cies of  beetles  challenged  Darwin  to  discover  a  reason,  the 
flight  of  birds  and  insects  challenged  Langley  and  Wright 
to  find  some  mechanical  means  of  imitating  them.  Each 
suggestion  that  ideas  may  be  reahzed  starts  the  discoverer 
on  a  quest  for  the  means.  Granted  the  problem,  the  next 
stage  is  an  analysis  of  the  problem  into  its  elements  or 
conditions  to  obtain  a  better  understanding  of  what  is  to 
be  done. 

Judgment 

Judgment,  the  First  Active  Step  in  Reasoning.  —  The 

first  step  either  in  understanding  a  situation  or  in  finding 
a  way  out  of  a  difficulty  is  an  analysis  of  the  situation. 
This  process  of  analysis  consists  of  a  reference  of  each  part 
of  the  problem  to  its  pecuHar  concept  or  class.  The  pro- 
cess of  reference  to  a  type  is  known  as  the  judgment.  In 
the  solution  of  any  mechanical  problem,  the  building  of  a 
bridge,  for  example,  it  is  necessary  to  reduce  the  various 
strains  to  their  components,  to  measure  the  intensity  of 
each,  before  means  can  be  found  for  resisting  them.  In 
designing  a  building,  the  engineer  goes  beyond  the  ordi- 


JUDGMENT  425 

nary  rule  of  thumb,  determines  how  much  pressure  the 
building  will  exert  downward,  how  much  will  be  expended 
in  lateral  thrusts,  what  the  wind  pressure  is  Ukely  to  be  at 
a  maximum,  and  only  when  these  various  components  of 
the  problem  have  been  determined  is  he  ready  to  decide 
what  material  must  be  used  and  how  the  structural  ele- 
ments may  be  distributed.  Each  of  these  steps  is  an  analy- 
sis of  the  problem  into  simpler,  known  elements.  The 
process  of  analysis  is  essential  at  every  step  in  advance  of 
action.  It  consists  in  referring  the  new  to  old  and  famihar 
experiences  so  far  as  the  new  offers  points  of  similarity 
with  the  old.  This  is  the  first  place  at  which  the  back- 
ground of  older  experience  aids  in  the  new  construction,  in 
progress  of  any  sort.  Only  in  so  far  as  the  problem  can  be 
reduced  to  its  parts  and  the  parts  referred  to  established 
concepts  can  it  be  said  to  be  understood,  and  only  then 
is  it  possible  to  go  ahead  safely.  To  act  before  the 
situation  is  understood  is  to  act  in  the  dark  and  in- 
effectively. 

The  process  of  judging  consists  of  the  reference  of  a  new 
experience  or  an  entering  sensation  to  an  old  concept. 
From  one  point  of  view  it  is  simply  the  perception  process 
over  again.  A  stimulus  presents  itself,  and,  before  it  is 
really  conscious,  it  is  referred  to  some  old  type;  it  is  given 
a  meaning,  and  thereby  becomes  fully  conscious.  The 
process  called  judgment  by  the  formal  logician  is  approxi- 
mately the  same,  although  more  expHcit  and  definitely  rep- 
resented in  words.  Thus  'man  is  mortal'  is  a  judgment; 
man  is  the  subject,  mortal  is  the  predicate.  The  subject 
represents  the  presented,  the  thing  given  to  be  understood, 
and  the  predicate  the  concept  by  which  it  is  explained. 
The  process  of  judging  brings  the  new  under  some  head  or 
category  already  established. 


426        FUNDAMENTALS   OF   PSYCHOLOGY 

Judgments  of  Relation  and  Evaluation.  —  In  addition 
to  this  use  of  the  term  'judgment'  to  designate  the  reference 
of  the  unknown  to  some  definite  concept,  psychologists 
use  it  also  to  indicate  comparison  and  evaluation,  uses 
more  closely  related  to  that  of  everyday  speech.  One  is 
said  to  judge  when  one  compares  two  lines;  and  also  when 
one  estimates  the  value  of  anything,  assigns  the  money 
value  to  a  horse  or  other  article  of  merchandise,  or  esti- 
mates the  guilt  of  the  prisoner  at  the  bar.  In  each  case 
there  is  approximately  the  same  process.  In  evaluation  of 
any  kind,  one  has  a  scale  of  values  that  has  been  devel- 
oped in  the  course  of  many  experiences.  An  article  is 
given  its  place  in  the  list  on  the  basis  of  various  similarities 
to  things  judged  before,  some  explicit,  some  imphcit  and 
indefinite.  A  similar  process  is  present  in  judicial  deci- 
sions. A  particular  crime  is  referred  to  the  general  scale  of 
crimes  and  the  punishment  is  affixed  in  accordance  with 
the  scale.  Comparisons  are  also  references  to  concepts, 
but  the  concepts  are  typical  relations,  not  typical  things. 
Relations  are  as  truly  concepts  as  are  space  or  time.  The 
relations  of  greater  and  less  are  typical  relations,  developed 
to  make  it  possible  to  understand  certain  phases  of  experi- 
ence. To  measure,  it  was  necessary  to  develop  the  con- 
cepts of  relation  in  space  and  time  and  mass;  and  measure- 
ment is  the  foundation  of  civilized  hfe.  WheA  an  observer 
asserts  that  a  Une  is  longer  than  another,  he  merely  looks 
from  one  to  the  other  in  immediate  succession,  and  the 
concept  greater  or  less  suggests  itself;  the  pair  is  referred 
to  one  class  or  the  other  immediately.  The  process  is  just 
as  unitary  as  is  the  recognition  of  a  new  object  or  any 
similar  classification.  The  judgment  in  general  is  a  refer- 
ence of  a  new  thing  or  situation  to  a  famihar  head,  the  ref- 
erence of  a  particular  or  unknown  to  a  general  type,  a 


INFERENCE  427 

reference  that  prepares  one  to  treat  it  adequately.  In  our 
specific  practical  case,  it  is  a  process  of  analyzing  the  ele- 
ments of  the  problem  in  preparation  for  its  solution. 

Inference 

The  Process  of  Finding  a  Solution  of  the  Diffi- 
culty. —  When  the  problem  has  been  stated  and  under- 
stood, the  next  step  is  to  discover  a  solution.  Finding 
the  solution,  inference  in  our  sense,  consists  in  a  process 
or  series  of  processes  of  association.  If,  when  the  judg- 
ment is  attained,  the  new  situation  is  reduced  to  famihar 
elements,  the  solution  is  practically  completed.  The  older 
solutions  may  suffice  or  may  be  combined  in  the  attain- 
ment of  the  new  desired  end.  In  these  cases,  association 
under  the  suitable  more  general  forms  of  control  may  be 
all  that  is  necessary.  In  many  other  instances  the  process 
cannot  be  reduced  to  laws,  although  probably  each  sugges- 
tion is  controlled  by  definite  laws  of  association.  One  can 
be  sure  only  that  there  will  be  many  attempts  of  different 
sorts  before  the  solution  is  finally  reached.  Inference  has 
more  points  of  resemblance  to  the  efforts  of  an  animal 
struggling  to  get  out  of  a  box  or  of  the  man  with  a  new 
puzzle  than  to  the  ordinary  notion  of  the  action  of  a  cal- 
culating human  being.  In  these  cases  the  process  is  one  of 
repeatedly  trying,  with  a  readiness  to  reject  all  but  the 
right  solution. 

Inference  a  Process  of  Trial  and  Error.  —  When  a  per- 
son tries  to  solve  a  puzzle,  he  makes  one  movement  and 
than  another,  until  finally  by  chance  he  is  successful.  In 
thinking  out  the  solution  for  a  problem  very  much  the 
same  process  is  used  except  that  the  trials  are  only  in 
thought.  One  thinks  of  one  after  another  of  the  possible 
positions  of  earth  and  sun  in  trying  to  find  a  reason  for  the 


428        FUNDAMENTALS   OF  PSYCHOLOGY 

sun's  appearance  so  far  to  the  north  (to  continue  the  pre- 
vious example).  If  the  first  one  will  not  work,  another  is 
tried.  If  that  is  rejected,  a  third  is  presented.  The  process 
continues  until  one  is  hit  upon  that  seems  satisfactory.  In 
finding  a  solution  of  a  difficult  mechanical  problem,  the 
process  of  trying  suggestions  and  rejecting  them  may  last 
for  hours,  and  of  course  in  important  inventions  the  trials 
may  continue  for  years  before  the  right  solution  is  hit 
upon.  Frequently,  an  approximation  to  the  solution  will 
be  reached,  and  then  the  process  of  transforming  or  per- 
fecting will  go  on  by  the  same  method  for  an  equally  long 
time  before  what  can  be  considered  a  complete  solution 
will  be  hit  upon.  In  the  case  of  actual  inventions  or  the 
solution  of  actual  problems,  the  final  satisfaction  may  come 
almost  by  accident,  if  we  can  distinguish  between  accident 
and  intention  in  such  an  operation.  The  list  of  great  in- 
ventions that  have  been  made  by  accident  is  very  long. 
Almost  the  only  rule  that  can  be  given  for  the  attainment 
of  the  desired  end  is  to  keep  trying.  Persistence  is  the 
only  virtue;  the  rest  is  very  largely  a  matter  of  chance. 
There  are  certain  minds  in  which  ideas  spring  readily,  that 
seem  fertile  in  suggestions  of  all  sorts;  certain  others  that 
practically  never  get  away  from  the  commonplace,  from 
the  prosaic  memories.  Blessed  is  he  whose  psychophysical 
disposition  is  of  the  former  type.  The  man  who  happens 
not  to  possess  this  touch  of  genius  can  do  nothing  but 
substitute  persistence  and  methodical  trial  for  the  quick 
advances  of  the  chosen  few.  No  rules  can  be  given  for 
making  the  unfertile  brain  fertile,  nor  for  the  better  use  of 
the  fertile  brain. 

In  the  unusualness  of  the  associations  and  connections 
that  are  made  lies  the  one  point  of  similarity  between  the 
abnormal  or  insane  brain  and  the  brain  of  genius.     Both 


INFERENCE  429 

are  constantly  calling  up  ideas  in  connections  that  would 
be  impossible  to  the  average  mind.  Tests  of  the  associa- 
tions of  the  insane  show  that  their  range  of  associations  for 
a  given  set  of  words  is  very  much  greater  than  for  the 
normal  man.  The  results  obtained  by  the  man  of  genius 
prove  the  same  departures  from  the  commonplace,  —  in 
this  case  called  original.  The  difference  between  the  two 
sorts  of  mental  fecundity  is  found  in  the  nature  of  the 
originality.  In  the  insane  there  is  little  control,  the  asso- 
ciates are  not  at  all  restricted  by  the  nature  of  the  en- 
vironment, or  by  any  appropriateness  to  the  situation.  In 
the  effective  man  of  genius,  they  are  checked  and  re- 
strained to  correspond  to  the  wider  demands  of  the  mo- 
ment. The  second  still  more  important  difference  is  to  be 
found  in  the  repression  on  the  part  of  the  normal  man  of 
the  suggestions  that  are  not  suited  to  the  occasion.  The 
speech  of  an  insane  man  may  be  merely  a  'word  salad,'  an 
outpouring  of  words  in  any  connection;  in  the  normal 
these  absurdities  are  inhibited,  and  if  they  present  them- 
selves at  all,  only  those  are  uttered  that  pass  the  censor 
of  common  sense.  Abihty  to  distinguish  between  the  ap- 
propriate and  the  inappropriate  is  the  primary  mark  of 
the  normal  as  opposed  to  the  abnormal.  This  serves,  too, 
to  emphasize  the  stages  of  the  inference.  One  must  first 
have  the  suggestion  that  is  to  constitute  the  solution,  but 
must  also  have  the  capacity  of  knowing  when  the  right 
solution  has  made  its  appearance.  In  this,  reasoning  is 
one  more  process  in  which  we  must  distinguish  between 
obtaining  the  suggestion  and  passing  upon  it.  Sufficient 
freedom  in  suggestion  is  desirable,  but  absolutely  essential 
is  the  capacity  to  appreciate  the  right  suggestion  when  it 
comes,  and  to  be  satisfied  with  no  less  than  the  full  solu- 
tion. 


430        FUNDAMENTALS   OF  PSYCHOLOGY 

Sometimes  the  right  suggestion  comes  by  chance,  some- 
times it  appears  when  thinking  of  something  else,  some- 
times one  is  merely  fumbUng  with  the  object  that  one 
wants  to  improve  in  some  way,  and  makes  the  proper 
change  without  any  preliminary  thought,  sometimes  it  is 
said  inventions  have  been  dreamed.  Jastrow  quotes  an 
instance  of  an  archaeologist  who  dreamed  the  reconstruc- 
tion of  the  results  of  certain  of  his  excavations  and  found 
that  they  were  adequate.  It  is  said  that  the  eccentric  on 
the  steam  engine  was  invented  by  the  boy  who  had  been 
set  to  open  and  close  the  valves  when  the  piston  should 
change  its  direction.  When  he  saw  some  boys  he  wanted 
to  play  with,  it  chanced  that  he  saw  a  place  to  put  a  stick 
where  it  would  do  the  work  he  was  doing,  so  slipped  it  in 
and  went  off  to  play.  Whether  the  anecdote  be  true  o^- 
not  it  illustrates  how  inventions  may  be  made.  It  makes 
no  difference  how  the  suggestion  comes,  provided  it  is  rec- 
ognized as  appropriate  when  it  comes,  for  inference  is  then 
complete.  Obviously  it  is  quite  as  important  to  make 
proper  selection  from  among  the  suggestions,  as  it  is  to 
have  the  suggestion.  In  this  respect  reasoning  is  hke 
memory.  The  associations  that  arise  in  the  attempt  to  re- 
call, correspond  to  the  suggestions  in  reasoning.  Passing 
upon  the  correctness  of  the  recall  found  in  recognition  cor- 
responds to  acceptance  of  the  solution.  'We  have  seen 
that  this  is  also  true  of  the  typical  actions.  All  learning 
is  a  process  of  hitting  upon  a  movement  by  chance  and 
retaining  it  if  the  results  are  satisfactory. 

Belief  and  Proof 

The  Nature  of  Belief.  —  It  is  particularly  essential,  then, 
that  we  should  understand  this  testing  or  censoring  pro- 
cess in  connection  with  reasoning.    Two  phases  may  be  dis- 


BELIEF  AND  PROOF  431 

tinguished.  One,  belief,  is  implicit,  comes  immediately  and 
offers  no  definite  consciousness  of  the  conditions  that  lie 
behind  it;  the  other,  proof,  is  more  explicit,  in  that  it  at- 
tempts to  make  clear  why  the  thinker  beheves,  and  why 
others  should  accept  the  inference.  Belief  gives  no  war- 
rant for  itself;  a  man  knows  that  he  believes,  but  can  tell 
why  only  from  a  study  of  the  conditions  under  which  be- 
Hef  makes  its  appearance.  Neither  the  feeling  of  belief 
nor  the  conditions  that  compel  belief  are  fully  conscious. 
In  fact,  the  feeling  of  belief  can  be  described  best  in  nega- 
tive terms.  We  beheve  all  that  is  not  doubted,  —  the  per- 
sistent, unquestioned  presence  of  any  idea  constitutes  be- 
lief. Doubt,  on  the  other  hand,  comes  with  alternations  in 
the  interpretations,  is  due  to  a  constant  change  from  one 
to  another  of  the  ways  of  looking  at  an  object.  The  cause 
of  the  fluctuation  is  to  be  found  in  the  changing  points  of 
view  from  which  the  fact  is  considered,  —  in  the  different 
complexes  of  experience  that  serve  to  bring  up  first  one  in- 
terpretation, then  another.  Thus,  if  one  is  considering  a 
general  problem,  for  instance  a  favorite  of  the  economists 
—  the  advantages  of  controlled  monopoly  as  opposed  to 
unlimited  competition,  —  one  will  think  of  the  importance 
of  large  production,  of  the  encouragement  to  capital  from 
certain  returns,  on  the  one  side,  and  will  believe  in  monop- 
oly; when  one  thinks  of  the  tendency  of  human  nature  to 
think  first  of  its  own  advantages,  and  of  the  growing  cal- 
lousness of  the  dictator  to  those  dependent  upon  him,  per- 
mission to  combine  seems  undesirable,  and  behef  in  mo- 
nopoly is  refused.  The  checks  that  come  from  state  control 
will  remove  the  doubt  for  a  moment  until  the  difficulties  in 
exercising  impartial  control  present  themselves,  when  the 
old  doubt  reasserts  itself.  Doubt  is  an  expression  of  the 
conflict  in  various  beliefs,  and  the  beliefs  in  turn  depend 


432        FUNDAMENTALS   OF  PSYCHOLOGY 

upon  the  presence  of  various  groups  of  experiences  which 
make  for  the  prominence  of  one  attitude  or  another  to- 
ward the  assertion  that  is  questioned. 

In  its  less  explicit  forms  belief  seems  to  be  an  expres- 
sion of  the  harmony  of  a  particular  statement  with  the 
dominant  group  of  experiences.  This  may  be  seen  to  ad- 
vantage in  the  changes  in  belief  as  different  possibilities 
are  considered.  When  one  is  caught  off  one's  guard,  when 
a  proposition  is  viewed  in  the  light  of  a  limited  group  of 
experiences,  one  will  believe  things  which  would  not  be 
believed  under  ordinary  circumstances.  An  exaggeration 
of  the  condition  is  seen  in  the  dream,  where  we  may  as- 
sume that  large  areas  of  the  cortex  are  inactive,  and  only 
the  few  active  cells  control  consciousness.  Then  one  will 
believe  many  constructions  that  are  rejected  as  soon  as  one 
wakes.  The  dream  need  harmonize  only  with  the  partial 
consciousness,  but  as  soon  as  one  wakes  it  is  necessary  that 
it  harmonize  with  all  portions.  This  it  fails  to  do,  and  it  is 
then  at  once  seen  to  be  bizarre.  In  the  play  attitude,  or  in 
the  artistic  attitude  as  in  novel  reading,  one  may  volun- 
tarily hold  part  of  consciousness  out  of  action  and  pass 
upon  the  game  or  the  work  of  art  In  the  Hght  of  a  partial 
experience.  In  this  mood  the  result  is  accepted  as  true  for 
the  moment,  although  one  is  aware  that  it  will  not  seem 
true  as  absolute  fact.  In  general,  beHef  is  agreement  be- 
tween the  construction  of  the  moment  and  the  total  ex- 
perience. The  awareness  of  the  agreement  no  more  implies 
the  presence  in  mind  of  all  of  the  facts  that  are  involved  in 
passing  upon  the  experience  than  recognition  implies  the 
presence  of  the  associates  that  give  the  entering  impres- 
sion a  place  in  the  past,  or  the  meaning  of  an  image  in- 
volves the  full  presence  of  all  that  is  meant.  Rather  the 
thing  believed  merely  holds  the  centre  of  the  stage  without 


BELIEF   AND    PROOF  433 

wavering  or  opposition,  and  that,  with  possibly  some  slight 
feeling,  constitutes  belief. 

Proof  a  Justification  of  Belief.  —  While  belief  is  suffi- 
cient justification  for  a  conclusion  on  the  part  of  the  per- 
son who  believes,  the  conclusion  may  not  appeal  so  strongly 
to  the  listener  or  to  others.  It  is  this  fact  which  makes 
proof  necessary.  Since  justifying  the  conclusion  is  the  one 
part  of  the  reasoning  process  that  is  self-conscious,  it  is  the 
process  to  which  the  formal  logician  has  devoted  most  at- 
tention and  which  he  is  inclined  to  consider  the  only  part 
of  the  reasoning  process.  Two  forms  of  proof  are  to  be 
distinguished,  the  deductive  and  the  inductive.  The  typical 
deductive  proof  is  through  the  syllogism,  and  this  consists, 
in  essentials,  of  referring  the  particular  conclusion  to  some 
generally  accepted  principle,  to  a  general  law  that  is  typi- 
cal of  all  others.  Just  as  the  judgment  consists  in  refer- 
ring some  particular  object  or  difficulty  to  a  typical  diffi- 
culty or  concept,  the  proof  consists  in  finding  a  universal 
statement  under  which  the  particular  conclusion  that  has 
been  obtained  may  be  brought  and  thereby  made  to  seem 
true.  The  mere  mention  of  a  suitable  general  law  arouses 
the  peculiar  cortical  irradiations  of  associations  that  excite 
belief.  First  it  should  be  said  that  nothing  is  proved  that 
is  not  questioned.  For  one's  self,  behef  suffices,  and  for 
most  of  the  statements  of  everyday  life  as  they  are  made 
to  others  no  proof  is  necessary.  Proof  is  given  only  when 
one  hears  or  fears  objection  from  one's  listeners,  or  when 
one  desires  to  test  the  truth  of  the  conclusion  for  one's  self 
in  an  explicit  form. 

Deductive  Proof.  —  The  oldest  and  most  frequently  used 
form  of  proof  is  the  deductive.  In  essentials  this  consists 
in  referring  the  new  or  questioned  solution  or  invention  to 
an  old  or  familiar  class.    In  simple  cases  the  familiar  class 


434        FUNDAMENTALS   OF  PSYCHOLOGY 

is  merely  mentioned.  In  more  complicated  instances  the 
given  problem  is  analyzed  into  a  number  of  simpler  ele- 
ments and  it  is  shown,  as  in  a  problem  in  physics,  that  the 
solution  in  question  makes  use  of  a  number  of  the  simpler 
and  more  familiar  steps.  The  formal  logician  has  reduced 
proof  to  a  schematic  form  in  the  syllogism.  The  syllogism 
is  a  group  of  three  statements,  of  which  the  first  contains  a 
familiar  general  statement  which  is  used  to  justify  the 
conclusion.  The  statement  to  be  proved  is  put  last  and 
the  two  are  united  by  a  statement  which  indicates  the  rela- 
tion. The  general  statement  is  known  as  the  major  premise, 
the  connecting  statement  is  the  minor  premise,  and  the 
statement  to  be  proved  is  the  conclusion.  Thus  to  choose 
a  favorite  instance,  one  might  desire  to  prove  that  Socrates 
would  die  some  day  by  asserting  the  unquestioned  general 
principle  that  all  men  are  mortal.    This  takes  the  form 

All  men  are  mortal,  {Major  Premise) 

Socrates  is  a  man,  {Minor  Premise) 

Therefore  Socrates  is  mortal.         {Conclusion) 

The  reader  can  give  this  argument  a  setting  if  he  imagines 
the  members  of  the  Areopagus  arguing  over  the  feasibihty 
or  desirability  of  inflicting  the  death  penalty  upon  Socrates. 
This  syllogism  might  be  used  either  to  meet  the  statement 
that  it  was  not  possible  to  inflict  the  death  penalty,  be- 
cause of  the  prominence  of  Socrates;  or  it  might  be  made 
by  one  who  objected  to  the  death  penalty  on  the  ground 
that  Socrates  would  die  anyway  in  the  natural  course  of 
events  and  so  would  not  be  a  permanent  danger  to  the  state. 
It  is  obvious  that  the  incentive  to  the  syllogism  must 
come  from  some  one  who  has  asserted  the  conclusion,  and 
has  had  it  challenged.  The  syllogism  is  a  form  of  proof,  not 
as  is  frequently  asserted  a  method  of  reaching  conclusions. 


BELIEF   AND   PROOF  435 

The  syllogism  is  effective  for  proof  just  because  it  con- 
nects the  new  with  an  already  accepted  fact  or  group  of 
facts.  When  the  reference  has  been  made,  the  belief  that 
attaches  to  the  old  and  familiar  is  transferred  to  the  new. 
The  effect  seems  to  be  one  of  arousing  masses  of  old  ex- 
perience which  by  their  very  arousal  serve  to  stimulate  the 
belief  attitude.  The  statement  can  add  nothing  to  the 
new  and  must  already  be  known,  or  it  would  not  be  ac- 
cepted by  the  man  who  is  convinced.  The  utterance  of 
the  general  principle  seems  to  arouse  the  memories  of  the 
older  cases  and  to  crystallize  them.  Belief  follows.  The 
essence  of  the  syllogism  consists  in  this  reference  of  the 
doubted  to  a  familiar  group.  It  may  be  given  less  formal 
expression  and  be  equally  effective.  James,  for  example, 
shows  that  if  one  were  asked  why  one  placed  a  bit  of  match 
under  one  side  of  the  chimney  of  a  smoking  lamp,  the 
device  could  be  justified  by  saying  that  it  would  admit  air. 
The  value  of  this  might  be  questioned  also,  to  be  justified 
by  reference  to  the  fact  that  burning  is  a  form  of  oxidation 
and  will  not  be  complete  when  the  supply  of  air  is  defi- 
cient. If  that  were  questioned,  one  would  be  compelled  to 
refer  to  chemical  formulae.  In  fact  complete  proof  on  any 
point  might  require  reference  through  a  large  number  of 
steps.  Each  of  these  might  be  put  in  the  form  of  the 
syllogism.  Fortunately,  a  reference  to  one  more  general 
principle  in  any  brief  way  usually  is  sufficient  to  arouse 
behef. 

Inductive  Proof.  —  The  other  form  of  proof,  the  induc- 
tive, consists  in  counting  instances,  in  determining  how 
often  the  conclusion  is  true.  If  in  the  past  a  suggestion 
has  worked  on  every  occasion,  we  are  prepared  to  accept 
it  as  true.  The  effectiveness  of  this  proof  Kes  in  the  actual 
study  of  past  cases  or  in  experimental  repetition  and  veri- 


436        FUNDAMENTALS   OF   PSYCHOLOGY 

fication  of  the  conclusion.  From  a  study  of  the  vital  statis- 
tics one  knows  inductively  that  all  men  die.  One  knows 
that  an  aeroplane  will  fly,  because  it  has  flown.  The  whole 
proof  is  dependent  on  assuming  that  what  has  happened 
will  happen.  In  one  sense  the  two  proofs  tend  to  come  to- 
gether, since  of  the  empirical  proofs  only  those  are  accepted 
which  are  in  every  way  similar,  which  can  be  referred  to  the 
same  general  principle.  On  the  other  hand,  the  general 
principles  that  constitute  the  major  premises  of  syllogisms 
and  the  accepted  truths  are  probably  in  the  last  analysis 
derived  from  experience,  but  experiences  coordinated  and 
tested  by  particular  applications  and  by  their  harmony 
with  other  general  principles.  A  general  principle  fre- 
quently starts  as  the  result  of  a  few  observations,  is  tested 
by  other  observations,  then  is  compared  with  other  general 
principles  that  have  also  been  suggested  and  tested  by  other 
single  observations,  and,  if  all  harmonize,  it  gradually  comes 
to  be  generally  accepted.  In  most  subjects  controversies 
over  general  principles  are  current  at  all  times,  because 
each  is  in  harmony  with  certain  experiences  and  out  of 
harmony  with  others.  Settlement  comes  with  more  accu- 
rate analysis  of  the  problem,  with  more  careful  study  of 
the  facts,  and,  where  experiment  is  possible,  by  making 
crucial  tests  of  each.  But  in  no  case  is  it  possible  to  say  that 
organized  previous  experience  has  not  had  some  share 
in  the  proof,  nor  is  it  possible  to  assert  that  observation  of 
particular  experiences,  induction,  shall  not  have  contributed 
something.  When  reference  to  generahzed  earlier  experi- 
ence is  more  in  evidence,  the  proof  is  called  deductive; 
when  particular  cases,  statistics,  or  experiments  play  the 
larger  part,  the  proof  is  known  as  inductive;  but  neither 
can  be  completely  divorced  from  the  other. 


GENERAL   REMARKS   ON   REASONING     437 

General  Remarks  on  Reasoning 

Summary.  —  That  the  stages  of  reasoning  may  be  as  we 
have  stated  them —  (i)  the  presentation  of  the  problem 
that  comes  by  a  thwarting  of  the  progress  of  action  or  of 
thought,  (2)  the  judgment  or  analysis  of  the  problem  into 
its  elements  and  the  reference  of  each  to  its  appropriate 
class  or  concept,  (3)  the  inference  or  discovery  of  the  solu- 
tion by  much  casting  about,  and  finally  (4)  proof,  —  may 
be  seen  by  a  study  of  the  way  in  which  Darwin  and  Wallace 
developed  their  doctrine  of  natural  selection.  It  happens 
that  in  this  case  two  men,  travelKng  independently  prac- 
tically the  same  course,  arrived  at  the  same  conclusion,  and 
we  have  the  process  recorded  by  one  of  them  and  confirmed 
by  mutual  friends.  Dr.  Wallace, ^  in  modestly  disclaiming 
any  priority  to  Darwin  in  the  discovery,  traces  in  a  paper 
before  the  Linnaean  Society  the  facts  that  led  both  to 
hit  upon  the  idea  and  to  its  statement.  First  with  reference 
to  the  formulation  of  the  problem: 

"First  (and  foremost  as  I  beheve)  both  Darwin  and  myself 
became  ardent  beetle-hunters.  Now  there  is  certainly  no 
group  of  organisms  that  so  impresses  the  collector  by  the 
almost  infinite  number  of  its  specific  forms,  the  endless 
modifications  of  structure,  shape,  color,  and  surface-mark- 
ings that  distinguish  them  from  each  other,  and  their  in- 
numerable adaptations  to  diverse  environments.  .  .  . 
Again,  both  Darwin  and  myself  had,  what  he  terms  *  the 
mere  passion  of  collecting.'  ...  I  should  describe  it 
rather  as  an  intense  interest  in  the  mere  variety  of  Uving 
things  —  the  variety  that  catches  the  eye  of  the  observer 
even  among  those  which  are  very  much  aHke  but  which  are 
soon  found  to  difTer  in  several  distinct  characters.  Now  it 

1  The  Origin  of  the  Theory  of  Natural  Selection,  by  A.  R.  Wallace,  Pop. 
Sci.  Monthly,  Vol.  LXXIV,  pp.  398  ff. 


438        FUNDAMENTALS   OF  PSYCHOLOGY 

is  this  superficial  and  almost  childlike  interest  in  the 
outward  form  of  Kving  things  which,  though  often  de- 
spised as  unscientific,  happened  to  be  the  only  one  which 
would  lead  us  towards  a  solution  of  the  problem  of  species. 
...  It  is  the  constant  search  for  and  detection  of  these 
often  unexpected  differences  between  very  similar  creatures, 
that  gives  such  an  intellectual  charm  and  fascination  to  the 
mere  collection  of  these  insects;  and  when,  as  in  the  case 
of  Darwin  and  myself,  the  collectors  were  of  a  speculative 
turn  of  mind,  they  were  constantly  led  to  think  upon  the 
'why'  and  the  'how'  of  all  this  wonderful  variety  in 
nature  —  this  overwhelming,  and,  at  first  sight,  purposeless 
wealth  of  specific  forms  among  the  very  humblest  forms  of 
Hfe.  .  .  .  Then,  a  little  later  ...  we  became  travellers, 
collectors,  and  observers  in  some  of  the  richest  and  most 
interesting  portions  of  the  earth;  and  we  thus  had  forced 
upon  our  attention  all  the  strange  phenomena  of  local  and 
geographical  distribution,  with  the  numerous  problems  to 
which  they  give  rise.  Thenceforward  our  interest  in  the 
great  mystery  of  how  species  came  into  existence  was  in- 
tensified, and  —  again  to  use  Darwin's  expression  — 
'  haunted '  us. 

"Finally,  both  Darwin  and  myself,  at  the  critical  period 
when  our  minds  were  freshly  stored  with  a  considerable 
body  of  personal  observation  and  reflectioft  bearing  upon 
the  problem  to  be  solved,  had  our  attention  directed  to  the 
system  of  positive  checks  as  expounded  by  Malthus  in  his 
'Principles  of  Population.'  The  effect  of  this  was  analogous 
to  that  of  friction  upon  a  specially  prepared  match,  pro- 
ducing that  flash  of  insight  which  led  us  immediately  to 
the  simple  but  universal  law  of  the  'survival  of  the  fittest,' 
as  the  long-sought  effective  cause  of  the  continuous  modi- 
fication and  adaptation  of  li\ing  things." 


GENERAL   REMARKS   ON   REASONING    439 

This  shows  that  the  problem  had  been  set  for  both  by 
almost  the  same  conditions  and  that  the  solution  had  been 
attained  in  the  same  way,  but  the  method  of  proof  devoted 
to  the  suggestion  was  altogether  different.  Darwin  spent 
thirty  years  in  collecting  and  in  writing  out  the  evidence 
with  only  one  mention  of  his  theory  to  Sir  Charles  Lyell. 
Wallace,  on  the  contrary,  sat  down  at  once,  wrote  a  sketch 
of  his  theory,  and,  curiously  enough,  sent  it  to  Darwin  with 
the  request  that  it  be  pubUshed.  On  the  advice  of  friends 
Darwin  presented  the  paper  with  a  sketch  of  his  own  theory 
to  a  meeting  of  the  Linnasan  Society  July  i,  1858.  Darwin 
said  that  even  the  words  of  Wallace's  paper  were  so  nearly 
like  his  own  that  one  might  have  supposed  that  he  must 
have  seen  it  before  he  wrote.  Wallace  emphasizes  the 
influence  of  similar  circumstances  upon  the  common  result : 

"  This  \dew  of  the  combination  of  certain  mental  faculties 
and  external  conditions  that  led  Darwin  and  myself  to  an 
identical  conception  also  serves  to  explain  why  none  of  our 
precursors  or  contemporaries  hit  upon  what  is  really  so 
very  simple  a  solution  of  the  great  problem.  .  .  .  And 
now  to  recur  to  my  own  position,  I  may  be  allowed  to  make 
a  final  remark.  I  have  long  since  come  to  see  that  no  one 
deserves  either  praise  or  blame  for  the  ideas  that  come  to 
him.  .  .  .  Ideas  and  beHefs  are  certainly  not  voluntary 
acts.  They  come  to  us  —  we  scarcely  know  how  or  whence, 
and  once  they  have  got  possession  of  us  we  cannot  reject 
or  change  them  at  will.  It  is  for  the  common  good  that  the 
promulgation  of  ideas  should  be  free  —  uninfluenced  by 
either  praise  or  blame,  reward  or  punishment." 

In  this  sketch  Wallace  marks  out  expHcitly  three  of  our 
stages  —  the  arousal  of  the  problem,  the  hitting  upon  the 
solution,  and  the  proof.  The  second,  the  analysis  of  the 
problem  or  judgment,  can  be  seen  implicitly  in  the  manv 


440        FUNDAMENTALS   OF  PSYCHOLOGY 

forms  that  the  problem  took  as  the  how  and  why  of 
species  became  prominent  at  different  times.  Observation 
will  show  that  any  clearly  formulated  bit  of  reasoning 
takes  essentially  the  same  course.  Most  of  the  thinking 
of  our  daily  Hfe,  even  in  important  decisions,  stops  with 
the  implicit  belief.  The  formal  justification  of  the  conclu- 
sion is  not  made.  However,  as  we  have  seen,  the  unformu- 
lated but  organized  earher  experience  is  at  work  in  accepting 
or  rejecting  these  conclusions  through  the  immediate  behef 
processes,  just  as  it  is  in  the  more  formal  operations.  The 
warrant  is  the  same,  although  the  form  in  which  it  is  ex- 
pressed is  different. 

In  reasoning,  then,  we  see  an  advance  made  upon  the 
accumulated  knowledge,  but  an  advance  that  is  always 
made  possible  and  controlled  by  that  accumulated  knowl- 
edge. One  understands  the  new  presentation  and  the  new 
difficulties  in  terms  of  the  organized  old  experiences,  the 
types  and  concepts;  one  obtains  suggestions  for  new  solu- 
tions on  the  basis  of  analogies  with  the  old;  and,  when 
obtained,  the  suggestions  for  new  solutions  are  justified 
and  tested  in  advance  of  actual  use  in  the  hght  of  the  organ- 
ized knowledge.  While  new  experiences  and  new  trials  are 
constantly  increasing  the  sum  total  of  knowledge,  it  is  only 
by  virtue  of  the  previous  accumulations  and  organizations 
that  the  new  can  be  understood  and  that  one  may  venture 
to  test  the  new  suggestions  in  action  with  even  fair  assurance 
of  success. 

REFERENCES 

Titchener:  Experimental  Psychology  of  the  Thought  Processes. 

Dewey:  How  We  Think. 

Dewey:  Studies  in  Logical  Theory. 

Pillsbury:  The  Psychology  of  Reasoning. 


CHAPTER  XIV 
IMAGINATION  AND  DREAMS 

A  LARGE  part  of  our  life  sleeping  and  waking  is  spent  in 
mental  processes,  intermediate  between  remembering  and 
reasoning,  which  passes  under  such  terms  as  imagination, 
revery,  and  day  dreams.  Even  during  sleep  we  have  the 
conscious  processes  that  we  know  as  dreams.  These  various 
processes  are  ahke  in  that  they  are  due  to  largely  uncon- 
trolled associations  which  continue  without  definite  purpose 
and  give  pleasure  because  of  the  nature  of  the  constructions. 
The  laws  of  origin  of  the  imaginative  processes  are  approxi- 
mately the  same  as  those  for  memory  and  reasoning,  but 
the  ends  and  controUing  processes  are  very  different. 
Reveries  are  evoked  in  accordance  with  the  laws  of  associa- 
tion, as  are  memories  and  the  products  of  reasoning;  but 
the  constructions  are  new,  and  consequently  cannot  be 
recognized,  as  the  products  of  memory  can.  At  the  same 
time  imagination  differs  from  reasoning  in  that  reveries 
have,  at  most,  a  very  hmited  truth;  they  are  not  believed, 
or  are  beheved  to  be  true  only  under  very  special  condi- 
tions. If  we  seek  the  criteria  of  the  group  we  find  it  in  a 
lack  of  definiteness  rather  than  in  any  positive  character- 
istics. It  is  marked  by  the  free  action  of  the  mental 
machinery. 

Imagination  and  Life.  —  It  is  into  this  type  of  mental 
life  that  we  fall  the  moment  we  are  free  from  a  serious  task. 
It  must  be  confessed  that  it  occupies  many  of  the  intervals 
in  serious  tasks,  in  many  cases  time  that  should  be  given 


442        FUNDAMENTALS   OF  PSYCHOLOGY 

to  the  duties  of  life.  When  the  clerk  at  his  desk  has  a 
moment  he  finds  himself  constructing  for  himself  a  world 
that  is  more  pleasant  than  that  in  which  he  hves.  The  stu- 
dent, during  the  uninteresting  periods  of  a  lecture,  finds  his 
mind  wandering  off  to  a  world  of  future  conquests,  or  to 
imagined  changes  in  his  lot.  The  ploughboy  fills  his  time 
picturing  a  state  in  which  he  will  sit  in  the  house  and  direct 
the  labor  of  others,  and  no  longer  hold  the  handles  of 
the  plough.  The  spare  time  of  all  alike,  high  or  low  in 
station,  intelHgent  as  well  as  unintelHgent,  is  spent  in  spin- 
ning fancies.  Thinking  towards  a  definite  goal  is  a  matter 
of  effort,  of  distinctly  greater  effort  than  the  purposeless 
wandering  of  the  mental  images. 

The  types  of  these  imaginings  range  from  passing  day- 
dreams, unrecorded  and  transient,  to  the  work  of  the  novelist 
or  the  poet,  and  the  creations  of  the  painter,  sculptor,  and 
musician,  on  the  one  hand,  and  to  the  great  constructive 
works  of  the  inventor  on  the  other,  as  the  im.aginative 
process  merges  with  reason.  If  we  were  to  give  a  complete 
explanation  of  these  simpler  states  of  mind  we  would  at 
once  have  a  theory  of  art,  in  all  of  its  forms,  and  of  certain 
of  the  achievements  of  the  inventor. 

Play 

Imagination  and  Play.  —  One  can  find  an  analogy  for 
operations  of  imagination  in  the  purposeless  activities  of 
animals  and  children,  which  we  call  play.  Here  on  the 
active  side  we  have  the  same  series  of  tendencies,  probably 
the  same  control  or  lack  of  control  that  we  find  in  the  men- 
tal state  that  we  have  been  describing.  The  cause  of  play 
is,  like  the  process  of  imagination,  the  inability  to  keep 
still,  the  activity  of  the  neuromuscular  mechanism,  that 
must  respond  to  every  stimulus  with  movement.     This 


PLAY  443 

overflow  of  activity,  the  inability  to  remain  quiet,  explains 
the  constant  movement  of  the  child;  it  does  not  explain 
the  particular  form  that  the  movements  shall  take.  Many 
of  the  movements  are  determined  as  much  by  the  operations 
of  the  laws  of  imagination  as  is  the  mental  process  itself. 

Play  as  Instinct.  —  Some  plays  are  definitely  instincts; 
but  again,  as  in  imagination,  the  instinct  is  evoked  by  a 
stimulus  or  situation  other  than  that  to  meet  which  the 
instinct  was  evolved.  Plays  are  instincts  appHed,  in 
advance  of  their  actual  need,  to  situations  similar  to  those 
that  will  demand  their  appUcation.  The  fighting  plays  of 
boys,  and  the  playing  with  dolls  and  at  housekeeping  of 
girls,  are  both  sets  of  activities  which  will  be  called  into  use 
later.  In  these  games  what  is  instinctive  is  not  so  much 
the  motor  response  as  it  is  the  pleasure  that  comes  in  think- 
ing and  acting  out  the  situation.  There  is  an  instinctive 
pleasure  in  fondling,  and  dressing  the  doll:  but  it  is  a  ques- 
tion whether  the  doll  would  evoke  the  instinct  unless  it  were 
thought  of  as  a  child.  Not  the  instinct  but  the  imaginative 
transformation  of  the  doll  into  a  child,  and  the  change  of 
the  situation  as  a  whole  into  the  home  situation,  constitutes 
the  essential  of  the  play  experience.  This  setting  changes, 
and  the  reaction  with  it.  The  doll  may  be  thrown  down 
or  hidden  in  a  basket  when  the  game  is  over,  as  a  real  child 
would  not  be.  It  is  a  child  only  while  the  game  is  on.  This 
make-believe,  with  the  changes  in  the  character  of  the 
assumptions  with  changing  attitude,  is  what  is  at  the  bottom 
of  the  play  motif.  It  makes  it  possible  for  the  child  to  act 
out  situations  which  are  pleasant  to  him,  which  he  is  not 
able  to  attain  in  reality. 

The  games  give  opportunity  for  the  expression  of  the 
various  instincts.  In  addition  to  the  household  games 
that  are  indulged  in  mainly  by  the  girls  and  which  are 


444        FUNDAMENTALS   OF  PSYCHOLOGY 

pleasant  because  of  the  appeal  to  racial  instincts,  we  have 
games  of  contest,  which  may  permit  expression  of  the 
primitive  fighting  instincts,  or  the  plays  of  skill,  which  in- 
dulge merely  the  instinct  of  rivalry,  in  its  varied  forms, 
coupled  with  the  pleasure  in  acquirement  of  skill  for  skill's 
sake.  Any  game  or  instrument  which  increases  capacity, 
which  gives  a  chance  for  a  struggle  with  possible  assurance 
of  superiority  over  some  one  else,  is  pleasant.  The  over- 
coming of  danger,  the  accumulation  of  real  or  imaginary 
valuables,  as  in  games  of  chance,  are  pleasant  because  of 
the  appeal  to  the  individual  instincts.  The  games  that 
involve  rivalry  and  the  use  of  instruments  that  increase  the 
power  of  the  individual,  give  a  satisfaction  because  of  appeal 
to  the  sense  of  individual  importance,  and  may  therefore 
be  classed  under  the  games  that  appeal  to  the  social  in- 
stincts. In  practically  every  case  the  pleasure  of  the 
game  is  instinctive,  but  it  is  always  itself  a  product  of  the 
imagination  which  constructs  a  situation  representing  some 
other  real  situation  that  would  evoke  the  instincts  in 
question. 

Revery 

Day-dreams  Involve  Instinctive  Elements.  —  The  same 
general  statements  may  be  made  of  revery  or  day  dreaming. 
In  the  revery,  one  spends  time  in  permitting  the  construc- 
tion of  situations  in  idea  that  would  be  pleasing  were  they 
present  in  reality.  Some  of  these  constructions  are  real 
plans  for  the  future.  Many,  however,  are  nothing  more 
than  play  ideas,  in  which  one  thinks  merely  how  pleasant 
it  would  be  if  the  imagined  constructions  should  come  true. 
One  is  pleased  by  the  mere  passing  of  the  ideas  and  has  no 
thought  of  attempting  to  make  the  desired  or  imagined 
situation  real.  Constructions  are  pleasing  because  they 
put  the  individual  into  situations  where  he  could  satisfy 


REVERY  445 

his  instincts.  He  thinks  of  himself  as  rich  beyond  any 
degree  that  his  status  warrants  as  possible;  he  thinks  of 
himself  as  writing  books  that  would  give  him  renown;  he 
pictures  himself  as  doing  deeds  of  valor  on  the  battle  field ; 
or  of  rescuing  beautiful  ladies  who  shall  reward  him  with 
their  love.  Self-aggrandizement,  success,  social  appreciation, 
are  all  his,  in  his  reveries.  They  satisfy  the  same  instincts 
and  impulses  as  do  his  games,  aside  from  the  desire  for 
actual  physical  exercise  and  the  rehef  of  tension  that  is 
derived  from  motor  activity.  Like  play,  it  is  a  process  of 
make-believe;  but  the  make-beUeve  is  limited  to  ideas,  it 
does  not  extend  to  action. 

Control  of  Revery.  —  We  may  assume  that  the  course  of 
the  ideas  is  determined  by  the  laws  of  association.  Each 
idea  that  appears  and  each  object  that  is  seen  starts  a 
series  of  ideas,  by  the  mere  spread  of  the  impulse  to  the 
other  neurones  that  have  been  connected  with  it.  As  a  j/' 
rule  mass  dissolves  into  mass  in  the  process  ordinarily  called 
association  by  similarity.  Pictures  of  considerable  com- 
plexity succeed  each  other  as  wholes.  The  explanation  for 
the  succession  is  the  connection  formed  between  elements, 
just  as  it  is  in  all  recall.  There  is  some  degree  of  control 
of  the  recall  through  the  attitude  and  wider  mental  settings. 
The  succeeding  ideas  are  in  large  measure  congruous  •  they 
all  tend  to  the  development  of  a  consistent  whole,  although 
the  purpose  may  be  httle  in  evidence  when  the  construction 
starts  its  course.  '  The  idea  that  shall  follow  a  given  idea  is  / 
determined  by  the  wider  setting,  the  objects  round  about, 
and  the  ideas  that  have  gone  before.  It  is  an  instance  of 
controlled  association,  although,  as  is  usual,  the  control 
is  not  in  evidence. 

The  factors  most  evidently  lacking  in  imaginings  of  this 
type  are  the  selection  processes  which  pass  upon  the  results 


446        FUNDAMENTALS   OF  PSYCHOLOGY 

in  both  reasoning  and  memory.  In  memory,  the  products 
of  association  are  recognized,  and  if  they  are  not  recognized 
as  having  been  present  before,  they  are  rejected,  and  new 
recall  is  encouraged  by  supplying  new  stimuli  to  the  asso- 
ciation processes.  One  thinks  back  to  the  point  where  one 
left  the  main  track  of  recall,  and  waits  for  something  else 
to  be  suggested,  or  one  looks  about  for  some  object  that  will 
suggest  the  idea  desired.  In  reasoning,  as  we  have  seen, 
there  is  also  a  definite  purpose,  and  one  waits  for  the  con- 
struction to  appear  which  can  be  believed  to  fulfill  or  satisfy 
the  purpose;  (the  suggestions  are  sometimes  as  httle  con- 
trolled as  in  imagination,  but  there  is  always  selection  from 
the  numerous  ideas  that  present  themselves  of  those  that 
fit  the  conditions. 

Selection  in  Revery  is  through  Instinct.  — ^  In  the  revery 
the  ideas  are  seldom  controlled  in  their  course,  and  there  is 
little  selection.  The  only  choice  exerted  is  in  not  permitting 
one's  self  to  dwell  on  the  uninteresting^'  When  uninterest- 
ing ideas  appear  for  too  long  a  time,  one  will  either  start 
a  new  train  of  thought  or  go  to  work.  The  interesting,  how- 
ever, is  not  necessarily  pleasant.  As  will  be  seen,  we  occa- 
sionally enjoy  picturing  ourselves  in  adversity,  and  as  over- 
come by  the  thrusts  of  an  unkind  fate.  One  usually  pictures 
one's  self  as  overcoming  the  obstacles  and  rising  to  new 
heights,  but  one  seems  at  times  even  to  enjoy  representa- 
tions of  one's  own  misfortune.  Reveries,  from  the  stand- 
point of  association,  are  mere  trains  of  thought  that  run 
their  course  with  a  minimum  of  control  in  accordance  with 
the  simpler  laws  of  association,  subject  only  to  the  veto 
of  the  boresome. 

The  Unconscious 

Freud's  Theory  of  the  Unconscious.  —  In  connection  with 
this  and  all  of  the  other  forms  of  imagination,  from  dreams 


THE   UNCONSCIOUS  447 

to  humor,  we  should  mention  the  theory  of  Freud,  which 
has  been  attracting  the  attention,  particularly  of  the  physi- 
cian, for  the  past  two  decades.    For  Freud,  the  explanation 
of  any  mental  operation  that  is  strongly  emotionally  toned 
is  to  be  found,  not  in  the  laws  of  association  which  we 
have  emphasized  throughout,  but  in  the  work  of  what  he 
calls  the  subconscious  or  unconscious.    According  to  Freud, 
one  must  recognize  two  levels  of  consciousness  or  mind: 
one  we  have  been  studying  so  far;    the  other  lies  hidden 
below  that,  and  is  not  open  to  observation  by  the  individual. 
Its  action  can  be  inferred,  merely,  from  the  nature  of  the 
mental  processes  and  the  behavior  of  the  individual.    The 
desires  of  the  subconscious  are  the  primitive  ones  deter- 
mined by  instincts.    They  are  opposed  by  what  he  calls  the 
censor,  which  corresponds  pretty  closely  to  what  we  have 
been  calling  social  pressure,  the  influence  of  social  conven- 
tions and  ideals  which  will  not  permit  the  ideas  of  Hnes  of 
conduct  suggested  and  determined  by  these  instincts  to  rise 
into  consciousness.     Freud  goes  so  far  as  to  picture  the 
unconscious  as  a  person,  Kke  the  conscious  self  as  a  whole, 
which  has  definite  desires,  and  also  can  seek  different  means 
of  accompHshing  the  desires,  some  of  which  are  very  much 
like  reason.    We  are  to  think  of  mental  life  as  a  struggle 
between  two  persons,  one  impelled  altogether  by  instincts 
in  the  desire  to  gratify  the  individual  —  and  in  Freud's 
theory  particularly  the  racial  instincts;    while  the  other 
lives  a  Hfe  of  convention,  in  accordance  with  the  rules  of 
good  form.    The  latter  is  the  conscious  Hfe,  which  knows 
its  own  ends;   the  former  is  always  concealed,  and  while  its 
aims  are  known  to  itself,  presumably,  they  never  appear 
above  the  threshold.    The  upper,  conventional  mind  is  the 
mind  we  know,  or  are  presumed  to  know;  while  the  hidden 
motives  come  mostly  from  the  subconscious. 


448        FUNDAMENTALS  OF  PSYCHOLOGY 

Dreams 

Freud's  Theory  of  Dreams.  —  The  application  of  this 
theory  is  seen  most  completely  in  the  explanation  of 
dreams.  Dreams,  for  Freud,  are  always  attempts  of  the 
unconscious  to  force  its  desires  upon  the  upper  conscious- 
ness. Possibly  it  would  be  more  in  accordance  with  the 
spirit  if  not  the  letter  of  Freud  to  say  that  they  are  a  means 
by  which  the  man  as  a  whole  enjoys  the  thoughts,  desires, 
and  memories  which  are  usually  the  perquisite  of  the  sub- 
conscious alone.  It  seems  at  least  that  were  the  enjoyment 
Hmited  to  the  subconsciousness,  it  might  receive  quite  as 
much  satisfaction  in  dwelKng  on  the  desires,  or  revelling 
in  forbidden  memories  alone,  and  would  have  no  reason  to 
share  them  with  the  upper,  apparently  unwilling,  Puritani- 
cal over-lord.  Whatever  the  incentive,  the  Freudians  assure 
us  that  dreams  are  vehicles  of  the  thoughts  and  desires  of 
the  unconscious. 

But  even  in  sleep  the  censor  is  not  altogether  off  guard, 
and  in  consequence  it  is  necessary  to  outwit  it  by  various 
stratagems.  All  dreams  are  asserted  to  be  suppressed 
wishes.  When  the  wishes  are  distasteful,  the  dream  actually 
expresses  the  opposite  of  one's  real  desire,  or  the  dream  is 
clothed  in  symbols,  which  seem  innocent,  but  which  the 
unconscious  understands  to  be  really  sexual  in  meaning. 
It  is  asserted  that  the  joy  which  the  upper  consciousness, 
which  does  not  understand  the  symbolism,  obtains  is  a 
vague  reflection  of  the  dehght  of  the  unconscious.  It  should 
be  added  that  Freud  insists  that  the  dream  usually  starts 
from  or  is  suggested  by  an  event  of  the  preceding  day,  which 
serves  to  recall  some  experience  of  childhood  which  made 
a  strong  impression  because  of  its  emotional  content.  For 
Freud,  these  experiences  are  always  sexual  in  character,  and 


DREAMS  449 

hence  always  hide  behind  symbols.  It  should  be  said  that 
many  Freudians  widen  the  meaning  of  the  sexual  to  include 
other  closely  related  instinctive  activities  and  feeHngs,  an 
extension  which  obviates  certain  of  the  difficulties  we  have 
emphasized. 

Interpretation  of  Dreams.  —  The  difficulty  in  inter- 
preting the  dream  lies  in  the  fact  that  it  may  either  be  a 
wish  directly  expressed,  or  the  reverse  of  the  real  wish, 
or  it  may  mean  something  altogether  different,  that  can 
be  determined  by  reference  to  the  symboHc  relations  known 
by  experience  to  the  physician.  If,  for  example,  one  dream 
that  a  friend  is  dead,  it  may  mean  either  that  one  really 
wishes  he  were  dead,  or  by  opposites,  that  he  should  enjoy 
renewed  and  abundant  health.  Since  for  Freud  many 
common  objects  have  a  symbolic  meaning,  and  all  mean 
something  sexual,  it  is  always  easy  to  interpret  the 
dream  as  meaning  what  the  interpreter  wishes  it  to  mean. 
A  serpent,  a  flower,  a  landscape,  a  room,  falling,  are  for 
Freud  all  sex  symbols.  Obviously  it  is  somewhat  disquieting 
to  tell  dreams  to  a  convinced  Freudian,  as  some  of  the 
accepted  means  of  interpretation  would  be  sure  to  make 
possible  a  sexual  interpretation. 

Dreams  Explained  by  Association.  —  The  alternative 
interpretation  of  dreams  is  that  they  are  mere  association 
processes,  which  run  their  course  without  the  usual  controls. 
Ordinarily  the  dream  starts,  as  Freud  says,  with  some 
stimulation  left  over  from  the  day  before.  This  suggests 
ideas  from  the  more  or  less  remote  past,  as  Freud  asserts, 
but  we  may  assume  that  the  ideas  that  come  are  aroused 
by  the  ordinary  laws  of  association. 

Dreams  may  be  initiated  by  external  stimuli.  Cold 
water  appUed  to  the  face  may  produce  a  dream  of  being 
out  in  a  snow  storm,  or  more  complicated  constructions. 


450        FUNDAMENTALS  OF  PSYCHOLOGY 

Professor  Shepard  reports  that  in  an  experimental  investiga- 
tion of  the  circulation  in  the  brain  during  sleep,  the  patient 
showed  marked  changes  in  the  volume  of  the  brain  as 
men  passing  spoke  outside  the  window.  The  patient  was 
awakened  by  the  experimenter,  and  reported  a  lengthy 
dream  of  an  experience  at  a  party.  Numerous  similar  in- 
stances are  on  record.  Freud  insists  that  the  external 
stimulus  in  these  cases  serves  to  arouse  the  repressed  experi- 
ences only,  and  that  the  main  content  of  the  dream  is 
suppHed  from  the  subconscious.  On  the  other  explanation, 
the  sensations  would  arouse  associations  that  would  follow 
their  normal  course,  but  a  course  that  was  not  checked  or 
controlled  by  knowledge  as  in  the  ordinary  waking  state. 

Condensation  in  Dreams.  —  All  psychologists  agree  that 
dreams  are  much  condensed.  They  are  merely  hinted  at 
or  represented  by  the  content  of  the  dream.  When  re- 
called they  are  much  elaborated.  Freud  would  make  the 
condensation  even  greater  than  the  other  workers,  for  he 
beheves  that  the  dreamer  is  not  aware  of  many  of  the 
meanings  that  are  implied,  but  that  these  must  be  supplied, 
if  at  all,  by  the  physician  who  interprets  the  dream  by 
symbolism.  Each  object  has  some  hidden  meaning  which 
can  only  be  elaborated  by  one  who  knows  all  the  significance 
of  the  symbols.  In  addition,  the  important  parts  of  the 
dream  are  likely  to  be  displaced,  so  that  they  are  made  to 
occupy  a  much  less  prominent  place  than  they  should  have, 
in  the  interest  of  throwing  the  consciousness  off  the  scent. 
Both  condensation  and  displacement  are  according  to  Freud 
means  of  conceahng  the  real  meaning.  The  truth  is  not 
recognized  by  the  dreamer  even  in  his  most  complete  in- 
terpretation or  reproduction  of  the  dream.  Havelock  Ellis 
and  most  other  writers  who  are  not  Freudians,  on  the 
other  hand,  believe  the  condensation  to  be  a  short-hand 


CRITIQUE   OF   FREUD'S   THEORY         451 

representation,  for  which  the  dreamer  holds  the  key,  and 
which  he  elaborates  in  his  recall  without  knowing  that  the 
dream  was  in  short-hand. 

Other  Experiences  of  the  Unconscious 
AND  A  Critique  of  Freud's  Theory 

Freud's  Theory  of  Revery.  —  If  one  transfer  the  Freudian 
explanation  of  dreams  to  the  day-dream  and  ordinary 
revery,  it  would  hold  here,  too,  that  the  imaginary  con- 
struction was  the  expression  of  the  subconscious,  and  that 
the  material  of  the  day-dream,  particularly  of  those  parts 
that  give  the  most  pleasure,  are  to  be  interpreted  by  sym- 
bols as  meaning  what  they  do  not  seem  to  mean.  It  is 
probably  true  that  some  of  our  day-dreams  are  the  expres- 
sion of  wishes;  hardly  likely,  however,  that  these  wishes 
are  often  concealed  under  the  form  of  contraries.  Freud 
would  have  certain  of  them  run  as  symbols,  still  more  take 
the  form  of  expression  of  a  desire  under  its  opposite,  so  that 
one  would  build  elaborate  constructions  in  which  one  came 
off  second  best,  or  would  think  of  misfortunes  befalling 
members  of  one's  family,  when  one  was  really  enjoying 
thoughts  of  triumph.  One  may  at  least  say  that  the  dream 
and  the  day-dreams  have  the  same  explanation,  even  if 
one  does  not  decide  whether  the  Freudian  or  the  general 
association  theory  is  the  more  satisfactory. 

A  Critique  of  Freud's  Theory.  —  The  objection  to  the 
Freudian  theory  as  a  whole  lies  first  in  his  general  con- 
ception of  the  unconscious.  One  cannot  know  what  there 
is  in  the  unconscious,  because  by  hypothesis  it  is  altogether 
removed  from  observation.  It  is,  furthermore,  undesirable 
to  give  explanations  in  terms  of  assumptions  that  cannot 
be  verified.  Again,  the  Freudian  explanation  is  so  general 
that  it  applies  to  everything  and  therefore    to  nothing. 


452        FUNDAMENTALS   OF  PSYCHOLOGY 

It  is  just  as  much  a  question  why  the  unconscious  should 
desire  to  dwell  on  sex  matters,  or  why  it  should  desire  to 
forget  certain  events,  as  why  the  conscious  should  have  the 
same  attitude  or  desire.  There  is  no  chance  for  a  specific 
explanation  of  any  of  these  mental  events  when  once  they 
are  put  in  the  unconscious.  Were  there  any  certainty  that 
the  unconscious  existed,  these  lacks  would  not  prove  fatal. 
But  as  long  as  we  have  no  absolute  evidence  of  its  existence, 
and  there  is  no  particular  advantage  in  assuming  it,  the 
assumption  seems  uncalled  for.  A  more  serious  logical 
difficulty  with  the  Freudian  explanation  arises  from  the 
very  ingenuity  of  the  theory  of  symbols.  The  symbols 
include  practically  all  of  the  objects  that  commonly  appear 
in  dreams,  and  they  all  symbolize  the  same  experiences. 
If  all  dreams  signify  the  same  thing,  and  that  thing  is  some- 
thing that  sooner  or  later  is  bound  to  enter  into  the  experi- 
ence of  any  individual,  it  seems  to  follow  that  the  assump- 
tion is  proved.  When  one  attempts  to  show  fromx  this  that 
the  ideas  are  really  symbols,  the  proof  is  absolutely  incon- 
clusive. It  amounts  to  nothing  more  than  reasserting  the 
assumption,  and  then  stating  that  every  one  dreams  in 
symbols.  Brilliant  as  is  the  hypothesis,  one  cannot  regard 
it  as  established  or  capable  of  being  established.  It  has 
proved  of  practical  value  in  suggesting  means  of  treating 
patients,  but  it  cannot  be  highly  esteemed  as-  an  explanation 
of  mental  operations. 

Freud's  Theory  of  Forgetting.  —  The  Freudian  theory 
has  been  extended  to  explain  many  other  phenomena, 
in  the  individual  and  race.  Freud  asserts  that  the  dis- 
inclination of  the  unconscious  to  face  certain  facts  explains 
many  cases  of  forgetting.  When  a  man  forgets  an  errand, 
it  is  because  the  errand  is  really  distasteful  to  the  dominat- 
ing subconscious.     One  forgets  the  present  intended  for 


CRITIQUE   OF   FREUD'S   THEORY  453 

the  individual  whom  one  does  not  like,  but  to  whom  one 
feels  under  obligation.  The  names  of  individuals  one  does 
not  like  are  forgotten,  even  when  they  have  been  frequently 
repeated  and  should  be  thoroughly  learned.  Similarly 
Freud  would  explain  accidents  in  which  objects  are  dropped 
and  broken  as  due  to  a  real  desire  to  break  the  objects. 
He  instances  a  case  in  which  he  had  broken  a  vase  in 
handHng.  On  thinking  back  he  found  that  the  vase 
was  a  present  from  a  person  whom  he  disHked,  and  he 
believed  that  the  unconscious  broke  the  vase  to  remove 
a  reminder  of  the  disHked  individual.  This  he  regards 
as  typical  of  accidents,  just  as  forgetting  the  disagreeable 
through  the  intention  of  the  unconscious  is  typical  of  for- 
getting in  general. 

Freud's  Theory  of  Wit.  —  Not  all  of  the  activities  of 
the  unconscious  are  undesirable.  Witty  remarks  Freud 
would  ascribe  altogether  to  the  unconscious.  Wit  always 
has  a  bitter  element  in  it.  This  he  asserts  is  not  intended, 
nor  is  the  probable  effect  seen  by  the  speaker.  The  un- 
conscious, with  its  usual  malevolence,  wounds  the  vic- 
tim when  the  upper  consciousness  might  be  well  disposed 
to  him,  or  at  least  unwilling  to  offend  the  conventions 
which  prescribe  considerate  treatment  for  all  with  whom 
one  comes  into  contact. 

Symbolism  in  Myths.  —  The  s>Tnbols  of  the  unconscious 
have  been  extended  to  explain  all  of  the  myths  of  the  race. 
Here  the  explanation  offered  by  Freud  is  that  the  folk 
mind  would  dwell  by  preference  upon  sex  matters,  but 
conventions  which  develop  (their  development  is  not  de- 
scribed) prevent  the  formulation  of  these  stories  of  deepest 
interest  in  direct  form.  In  consequence  the  early  bards 
and  men  of  olden  times  who  formulated  the  folk  tales  took 
advantage  of  the  device  of  expressing  the  ideas  in  sym- 


454        FUNDAMENTALS   OF  PSYCHOLOGY 

bolic  form,  and  the  psychoanalyst  alone  has  been  able  to 
interpret  the  real  truths  which  they  contain.  It  is  interest- 
ing to  ask  how  and  why  the  symbols  took  the  exact  form 
that  they  are  assumed  to  have  taken.  Jung  has  suggested 
that  they  in  some  way  became  part  of  the  inheritance  of 
the  race  and  have  been  handed  down  through  the  uncon- 
scious in  the  same  way  that  the  instincts  are  transmitted 
through  the  physiological  organism. 

The  whole  belief  in  symbols  is  one  of  the  least  satisfactory 
phases  of  the  Freudian  hypothesis.  There  is  no  way  of 
verifying  the  hypothesis,  because  the  unconscious  can  give 
no  direct  report.  The  only  excuse  for  the  assumption  is 
that  in  the  treatment  of  hysteria  a  patient  will  now  and 
again  report  a  dream  or  a  day-dream,  and  when  the  physi- 
cian has  assumed  from  the  theory  of  symbolism  that  there 
must  have  been  some  repressed  or  forgotten  sexual  experi- 
ence, he  has  been  able  to  confirm  its  existence,  by  psycho- 
analysis. This  confirmation  is  less  satisfactory  than  it 
would  be  if  any  of  the  symbols  meant  anything  other  than 
sex  in  some  of  its  forms,  or  if  the  physician  who  believed 
in  Freud  would  under  any  circumstance  be  satisfied  with 
anything  other  than  sex  memories  as  a  cause  of  the 
disease.  It  is  also  difficult  to  see  what  pleasure  could 
have  been  found  in  myths  whose  symbolism  had  re- 
mained undiscovered  until  thirty  centuries'  after  the  orig- 
inal formulation. 

Art 

Art  as  Play.  —  In  one  of  its  aspects  all  art  is  to  be  re- 
garded as  a  form  of  play.  The  novel  and  the  drama  are 
day  dreams  of  the  author  which  by  their  character  are 
instinctively  pleasing  to  the  reading  or  theatre-going  public 
as  a  whole.    The  stories  that  please  are,  as  a  rule,  stories 


ART  455 

which  represent  the  hero  in  activities  that  it  would  please 
us  to  share.  We  can  sympathize  with  his  victories,  and 
with  his  defeats  which  are  nearly  always  temporary  and 
which  give  zest  to  the  final  triumph.  From  the  more  in- 
tellectual side  they  may  be  considered  as  studies  of  the  laws 
of  human  conduct,  as  a  result  of  making  certain  assumptions 
and  determining  what  the  natural  outcome  must  be.  In  this 
sense  a  novel  or  a  drama  is  a  depiction  of  the  laws  of  human 
action,  which  permits  the  author  to  show  what  a  man  must 
do  under  a  series  of  circumstances,  where  these  circum- 
stances can  be  worked  out  free  from  the  many  unknown 
forces  which  are  constantly  interfering  with  the  action  of 
the  known  conditions  in  real  life.  This  intellectual  interest 
may  lead  one  to  find  pleasure  in  the  unpleasant  ending, 
thus  making  tragedy  vie  with  melodrama  in  appeal. 

Sculpture  and  painting  gain  part  of  their  appeal  from 
the  fact  that  they  put  day-dreams  in  form,  and  represent 
the  pure  conditions  of  form  in  a  way  that  frees  them  from 
the  accessory  chances  of  real  Kfe.  In  part  they  have  an 
appeal  from  the  representation  of  the  forms  that  have  a 
native  or  instinctive  beauty.  This  beauty  may  come 
from  association  with  other  events  or  objects  that  are  them- 
selves pleasing;  as  the  proportions  of  the  human  body 
seem  to  be  repeated  in  many  of  the  structures  that  please 
but  which  do  not  even  suggest  the  human  form.  It  may 
be  that  certain  forms  have  a  native  attraction,  with  no 
need  for  association  to  intensify  the  pleasure  that  comes 
from  them.  Our  purpose  here  is  merely  to  indicate  that 
art  has  in  it  certain  of  the  elements  of  play,  in  so  far  as  it 
is  a  representation  of  one  phase  of  life  under  the  assumption 
that  it  is  the  whole.  This  make-believe  unites  all  forms  of 
art  with  play,  as  with  the  day-dream. 

We  may  mention  the  explanation  of  the  Freudians  that 


456        FUNDAMENTALS   OF  PSYCHOLOGY 

art,  too,  is  a  form  of  symbolism  in  which  comparatively 
innocent  terms,  forms  and  ideas  represent  the  sex  factors. 
The  primitive  symbols  are  apphed  to  novels,  to  paintings, 
to  sculpture,  in  exactly  the  same  way  as  to  myths.  Pos- 
sible illustrations  readily  suggest  themselves.  For  the  sake 
of  completeness  we  may  assert  that  the  Freudians  find  the 
symbols  of  the  dream  life  embodied  in  many  of  the  forms 
of  art  as  in  the  myth.  The  method  of  proof  is  the  same  as 
that  for  the  other  applications,  in  the  similarity  or  fancied 
similarity  between  objects  depicted  in  art  and  the  symbols 
of  the  dream  and  myth. 

General  Remarks  on  Imagination 

We  see,  then,  that  the  dream,  the  day  dream,  or  revery, 
play,  and  all  the  creative  arts  —  in  particular,  the  novel 
and  drama,  painting  and  sculpture  —  have  many  character- 
istics in  common.  All  find  their  justification  primarily  in 
the  fact  that  they  please,  all  are  largely  random  activities, 
controlled  only  so  far  as  they  lead  to  a  pleasant  end,  but 
an  end  that  is  not  foreseen  in  advance.  All  ahke,  again,  are 
processes  that  are  indifferent  to  truth.  They  are  supposed 
to  reach  conclusions  that  are  at  most  but  partially  true; 
although  in  art,  by  pressing  home  what  is  true  under  certain 
assumed  conditions,  they  may  enforce  truths  that  could 
not  be  presented  in  the  more  compKcated  'teahties  of  Hfe. 
The  results  are  pleasing  because  they  harmonize  with  the 
instincts;  and  because  on  the  intellectual  side  they  often 
present  the  solution  of  real  problems  in  a  way  that  would 
not  be  possible  theoretically. 

One  explanation  of  the  causes  that  lead  them  all  to  take 
the  course  they  do  has  been  found  in  the  laws  of  asso- 
ciation, the  mere  connection  of  neurone  with  neurone,  on 
the  nervous  side,  controlled  by  the  wider  interaction  of 


GENERAL   REMARKS   ON   IMAGINATION     457 

large  masses  of  the  cortex  in  checking  the  elements  which 
do  not  harmonize  with  the  whole  and  in  furthering  the 
activity  of  those  parts  that  do  harmonize.  As  in  all  as- 
sociation processes,  we  do  not  know  what  is  coming  before 
it  comes.  At  the  most  the  individual  knows  what  the 
general  end  of  all  the  thinking  may  be  or  what  he  would 
like  it  to  be.  If  he  knew  more  it  would  not  be  necessary 
to  think. 

As  an  alternative  explanation  of  the  course  of  these  play 
types  of  thought,  we  have  the  assumption  of  Freud  that 
they  are  results  of  definite  intention  on  the  part  of  the  un- 
conscious. This  unconscious  we  none  of  us  know  directly; 
and  did  we  know  it,  we  would  have  once  more  the  problem 
that  we  have  with  the  conscious  as  to  why  its  thought  pro- 
cesses act  as  they  do.  Were  it  possible  to  know  as  much  of 
consciousness  as  we  are  assumed  to  know  of  the  unconscious 
we  would  have  no  occasion  for  the  hypothesis  that  the 
latter  exists.  If  we  were  to  assume  the  latter,  we  would 
need  the  same  study  of  the  laws  of  succession  of  its  ideas  as 
that  which  we  have  given  of  the  association  processes,  if 
the  explanation  is  to  have  any  value;  for  an  explanation, 
a  study  of  the  laws  of  connection  and  of  their  controls  is 
essential.  It  is  better  to  unify  them  and  explain  them 
all  in  terms  of  a  single  self,  than  to  assume  a  second  self 
which  would  in  its  turn  require  the  corresponding  explana- 
tions.     There   is   no    sufficient    reason    for   belief   in    an 

unconscious. 

REFERENCES 

Constance  Long:  Psychology  of  Phantasy. 
Freud:  The  Interpretation  of  Dreams. 
Frexjd:  Psychopathology  of  Everyday  Life. 
Rivers:  Instincts  and  the  Unconscious. 
Wood  worth:  Psychology.     Chapter  XIX. 


CHAPTER  XV 
FEELING  AND   AFFECTION 

The  first  of  the  processes  that  are  in  part  explained  and 
in  part  presupposed  in  instinct,  is  feehng,  the  tone  that 
colors  very  many  of  our  mental  states.  The  principal 
difficulty  in  the  discussion  of  feehng  Ues  in  the  fact  that 
the  term  has  no  exact  and  definite  meaning,  or  perhaps 
more  truly  has  a  number  of  meanings,  no  two  of  which 
are  altogether  reconcilable,  and  which  are  held  by  different 
men  of  nearly  equal  authority.  The  term  'feeling'  was 
originally  used  to  indicate  approximately  the  same  mental 
states  as  sensation.  We  still  use  the  term  popularly  as 
synonymous  with  the  sensations  of  touch  and  with  organic 
sensations.  It  is  also  used  to  indicate  any  conscious  state 
which  is  relatively  vague,  for  example,  to  designate  intuition 
as  opposed  to  the  more  expHcit  ways  of  reaching  conclusions 
by  reasoning.  We  also  use  the  term  technically  for  any 
less  definite  conscious  state.  Thus,  we  talk  of  a  feeling 
of  interest,  a  feehng  of  recognition,  a  feelintg  of  behef,  and 
many  similar  states.  These  states  are  definite  enough  as 
ways  of  being  conscious,  but  their  conditions  are  less  in 
evidence  than  those  of  sensation.  The  term  '  feehng '  is  used 
popularly  and  at  different  times  has  been  used  technically 
for  a  number  of  different  processes  which  have  nothing  in 
common  except  their  vagueness,  either  in  the  state  itself, 
in  its  reference,  or  in  its  conditions. 

Definitions  of  Feeling  and  Affection.  —  Evidently  we 
cannot  use  the  term  in  all  of  the  ways  enumerated,  and 
458 


FEELING  AND   AFFECTION  459 

we  are  the  more  justified  in  restricting  it  by  the  fact  that 
there  is  a  fair  consensus  of  opinion  among  psychologists 
who  have  written  recently  that  we  shall  use  it  to  designate 
a  single  process  or  pair  of  processes  commonly  known  as 
pleasure  and  pain,  or  more  accurately  pleasantness  and 
unpleasantness.  Since  the  bare  feeling  is  never  found 
alone  but  is  always  accompanied  by  sensation,  it  is  neces- 
sary to  distinguish  the  simple  element  from  the  complex 
of  sensation  and  feeling.  Thus,  in  a  headache  there  is  a 
definitely  localized  sensation  or  mass  of  sensations,  and 
in  addition  we  dislike  the  ache.  The  dislike  itself,  or  the 
form  that  it  takes  as  a  mental  process,  is  the  affection,  the 
unpleasantness.  No  one  would  deny  that  this  is  quite 
different  as  a  conscious  quality  from  the  sensation  itself. 
This  quaUty  with  its  opposite  is  what  is  defined  as  affection. 
The  complex  of  affection  with  sensation  is  known  as  a 
feeling.  Psychologists  thus  distinguish  affection  from 
feeUng  for  their  technical  usage.  Affection  is  the  bare 
fact  that  we  find  an  event  pleasant  or  unpleasant,  while 
feeling  is  used  to  indicate  the  complex  of  sensation  and 
affection.  Thus,  in  the  instance  above,  the  mere  un- 
pleasantness of  the  experience  connected  with  the  headache 
is  the  affection,  while  feeling  is  the  term  appHed  to  the  total 
experience.  What  is  meant  by  this  state  can  be  understood 
by  all,  but  can  be  accurately  defined  or  described  by  no 
one.  In  the  attempt  to  make  clear  what  is  meant,  we  must 
recall  what  was  said  concerning  concepts.  What  we  desire 
to  do  is  to  indicate  a  concept,  which,  together  with  the 
concept  of  sensation,  shall  serve  to  make  possible  a  de- 
scription of  the  most  general  phases  of  our  conscious  Ufe, 
and  to  which  we  may  refer  concrete  states  as  they  present 
themselves.  To  make  this  reference  is  all  that  can  be  done 
in  the  way  of  analysis,  and  it  is  helpful  in  all  descriptions 


46o        FUNDAMENTALS   OF  PSYCHOLOGY 

and  discussions.  Sensations  or  affections  are  said  to  be  the 
elements  of  consciousness,  but  that  does  not  mean  that 
they  are  ever  found  separately.  All  that  is  meant  is  that 
it  is  possible  to  discover  in  mental  states  a  sensational 
phase  and  an  affective  phase,  —  that  certain  states  are 
similar  by  virtue  of  the  fact  that  they  are  pleasant,  just 
as  certain  others  are  similar  by  virtue  of  the  fact  that  they 
are  green,  and  still  others  in  that  they  are  square.  For 
convenience,  then,  we  have  spoken  of  sensations  as  inde- 
pendent existences  and  shall  speak  of  affections  in  somewhat 
the  same  way,  as  if  affections  were  elementary  conscious 
states,  and  that  mental  states  might  be  compounded  out 
of  them  as  substances  are  compounded  out  of  chemical 
elements. 

Affection 

Affection  and  Sensation.  —  In  justifying  a  separate  dis- 
cussion of  the  affective  phase  of  consciousness,  we  must 
meet  two  objections.  First,  it  has  been  held  that  feeling 
is  only  a  special  kind  of  sensation;  second,  that  affection 
is  not  a  distinct  element  at  all  but  merely  an  attribute  or 
accompaniment  of  sensation. 

Affection  not  a  Special  Kind  of  Sensation.  —  In  answer 
to  the  first  position  it  should  be  pointed  out  that  affections 
are  unlike  sensations  in  that  they  have  no  special  sense 
organs.  Pleasure  may  come  as  the  result  of  the  stimulation 
of  any  sense  organ,  and  displeasure  similarly  may  be  the 
accompaniment  of  many  different  kinds  of  stimulations 
and  may  be  excited  through  many  different  sense  organs. 
The  argument  for  the  specific  sensations  of  pleasantness 
and  unpleasantness  seems  to  have  been  developed  on  the 
assumption  that  pain  and  unpleasantness  are  identical. 
As  we  have  seen,  there  is  a  special  sense  organ  for  pain  in 


AFFECTION  461 

the  skin  and  other  tissues,  and  if  pain  and  unpleasantness 
are  to  be  considered  identical,  the  sense  organ  for  both  is 
readily  supplied.  As  a  matter  of  fact  pain  and  unpleasant- 
ness do  not  mean  the  same  thing.  Pain  is  the  specific 
sensation,  and  unpleasantness  the  accompanying  reaction. 
One  may  see  this  most  clearly,  perhaps,  from  the  fact  that 
pain  is  not  necessarily  unpleasant.  Without  speculating 
as  to  the  pleasure  of  martyrs,  we  find  numerous  cases  in 
which  sHght  stimulation  of  pain  spots  is  pleasant,  as  in  the 
cold  of  a  bath,  or  the  fascination  of  pressing  gently  upon 
an  inflamed  spot.  While  pain  in  slight  intensity  may  on 
occasion  be  pleasant,  it  is  not  at  all  infrequent  for  un- 
pleasantness to  accompany  other  mental  processes  in  which 
there  is  no  excitation  of  a  pain  nerve.  Smells  are  unpleasant 
when  there  is  often  none  of  the  sharpness  that  represents 
the  excitation  of  cutaneous  sense  ends.  The  odor  of  decay- 
ing flesh  is  unpleasant  in  itself,  as  opposed  to  the  unpleasant- 
ness of  ammonia  or  chlorine,  which  is  in  part  due  to  the 
excitation  of  pain  nerves  in  the  mucous  membranes  of  the 
nasal  passages.  Unpleasant  combinations  of  colors  or  of 
tones  belong  in  the  class  of  experiences  unpleasant  in  them- 
selves, as  do  also  the  unpleasant  effects  derived  from 
unpleasant  spatial  and  temporal  relations,  the  unpleasant 
ideas  from  social  wrongs,  etc.  One  finds  a  long  list  of 
unpleasantnesses  that  cannot  be  referred  to  sense  pains. 

If  pain  be  not  identical  with  unpleasantness,  and  the 
pain  nerve  be  not  the  organ  of  the  unpleasant  affection, 
still  less  is  it  possible  to  find  a  specific  sense  organ  for 
pleasantness.  It  has  been  suggested  that  tickle  may  be 
the  pleasant  quahty,  and  that  there  is  a  specific  sense  organ 
of  tickle.  This  latter  statement,  however,  is  very  question- 
able. Tickle  spots  have  now  and  again  been  reported, 
but  the  report  has  seldom  been  confirmed,  and  has  never 


462        FUNDAMENTALS   OF  PSYCHOLOGY 

been  generally  accepted.  Granted  the  existence  of  the 
tickle  spots,  the  same  objections  hold  to  identifying  tickle 
with  pleasure  as  to  identifying  pain  with  unpleasantness. 
Tickhng  may  be  unpleasant  and  many  different  kinds  of 
pleasure  have  no  resemblance  to  tickling.  Evidently  even 
if  we  grant  the  existence  of  the  tickle  spots,  pleasure  must  be 
something  more  than  a  pecuHar  cutaneous  sensation,  just 
as  unpleasantness  is  distinct  from  and  in  addition  to  pain. 

Affection  is  not  Localized.  —  Other  objections  to  identi- 
fying affection  with  sensation  may  be  made  on  the  basis 
of  the  lack  of  accuracy  of  locaHzation  of  the  affections. 
Sensations  always  have  a  definite  place,  while  affection  is 
not  definitely  locaHzed.  One  is  displeased  or  pleased  in  no 
particular  part.  Exceptions  have  been  taken  on  the  basis 
of  organic  sensations,  but  organic  sensations  are  rather 
incorrectly  localized  than  unlocaHzed.  Another  distinction, 
which  rests  on  a  slightly  less  certain  basis  but  is  probably 
generally  vahd,  is  that  sensory  processes  are  more  objective 
while  the  affective  processes  are  more  subjective.  Sensa- 
tions usually  are  referred  to  the  outside  world,  while 
feelings  are  pecuUarly  personal,  pecuharly  one's  own. 

Affection  and  Attention.  —  Closely  related  to  this  are  the 
differences  with  reference  to  the  effects  of  attention  and  the 
influence  of  recall.  It  seems  fairly  well  assured  that  attend- 
ing to  a  feehng  tends  to  diminish  rather  thkn  to  increase  it, 
while,  as  was  seen,  attention  increases  the  effectiveness  of 
sensations.  In  passing  upon  this  statement,  one  should 
be  careful  to  distinguish  between  attending  to  the  stimulus 
or  to  the  sensation,  and  to  the  mere  accompanying  pleasant- 
ness or  unpleasantness.  If  one  think  of  an  aching  tooth, 
the  pain  is  increased  and  the  accompanying  unpleasantness 
with  it.  If,  however,  one  attempts  to  introspect,  to  ask 
how  and  why  this  sensation  is  unpleasant,  one  will  be 


AFFECTION  463 

likely  to  find  that  the  unpleasantness  diminishes  as  one 
becomes  interested  in  watching  the  feeling,  and  it  may 
disappear  altogether.  An  unpleasant  situation  bravely 
faced  tends  to  lose  much  of  its  unpleasantness.  The  same 
may  be  said  of  pleasantness.  In  practice,  a  constant  search 
for  pleasure  defeats  its  end.  A  pleasure  attended  to  tends 
to  diminish.  Lives  spent  in  pleasure-seeking  seem  never 
to  attain  their  goal.  The  only  way  to  make  sure  of  pleasure 
is  to  keep  in  mind  some  end  to  be  accomphshed  and  let 
the  pleasure  come  as  an  incident  to  its  attainment.  Keep- 
ing pleasure  itself  in  mind  destroys  it,  while  attending  to 
the  stimulus  increases  pleasure  as  well.  The  objective  and 
subjective  difference  may  be  said  to  be  one  phase  of  this 
influence  of  attention.  Objective  processes,  when  attended 
to,  increase;  while  a  purely  subjective  process,  particularly 
if  that  be  related  in  some  way  to  attention  itself,  would  not 
be  increased.  If  one  think  of  feeling  as  an  effect  of  attend- 
ing to  a  stimulus,  it  would  follow  that  when  attention  was 
not  fixed  upon  a  stimulus,  at  least  one  condition  of  feehng 
would  disappear,  and  the  feehng  with  it. 

An  Affection  is  not  Recalled.  —  This  subjective  character 
of  feeling  has  also  been  connected  with  another  character 
or  alleged  character  of  feehng,  namely,  that  it  cannot  be 
remembered.  It  is  asserted  with  some  warrant  from  obser- 
vation that  feeUngs  are  not  recalled.  This  statement  must 
be  carefully  guarded  and  restricted  if  it  is  to  be  accepted. 
The  warrant  for  it  is  to  be  found  in  the  fact  that  feelings 
toward  an  event  are  hkely  to  change  between  the  time  the 
event  is  experienced  and  the  time  it  is  recalled.  Thus  a 
social  faux  pas  that  caused  extreme  embarrassment  may 
later  arouse  only  amusement,  and  a  practical  joke  that  was 
much  enjoyed  at  the  time  may  be  recalled  with  chagrin. 
The  affection  alone  is  not  recalled  in  these  cases,  but  the 


464        FUNDAMENTALS   OF  PSYCHOLOGY 

event  is  recalled,  and  the  feeling  aroused  depends  upon  the 
circumstances  at  the  moment  of  recall.  This  does  not  mean 
that  one  cannot  remember  that  one  was  pleased  or  dis- 
pleased on  the  first  occasion;  one  remembers  the  fact,  but 
the  affection  is  not  reinstated.  The  memory  of  how  one 
felt  is  indirect,  is  in  terms  of  words  or  the  memory  of  the 
expression.  The  feelings  are  not  reinstated  as  the  sensory 
elements  may  be,  but  are  merely  represented  or  meant. 
The  feeling  at  the  time  of  recall  is  the  expression  of  the 
present  attitude  toward  the  event  rather  than  of  the  earlier 
attitude,  the  attitude  when  the  event  was  really  experienced. 

Altogether  there  seems  little  probability  that  affections 
are  merely  separate  sensations.  Pain  and  unpleasantness 
are  distinct,  and  pain  seems  to  be  the  only  sensation  which 
could  in  any  degree  be  confused  with  either  pleasantness 
or  unpleasantness.  Pleasant  sensations  have  no  existence; 
i.e.,  there  are  no  sensations  to  which  the  term  pleasant- 
ness could  always  and  regularly  be  applied  that  do  not 
have  a  distinct  sensation  quahty  in  addition.  To  as- 
sume that  any  of  these  sensations  could  be  regarded  as 
identical  with  the  feeling  qualities  is  out  of  harmony  with 
the  facts  of  distribution,  as  well  as  with  the  quaUties  of  both 
sensation  and  feeling.  The  more  definitely  qualitative 
differences,  the  different  influence  of  attention,  and  the 
difference  in  the  way  they  are  affected  in  recall,  all  reenforce 
this  conclusion. 

Affection  not  an  Attribute  of  Sensation.  —  The  second 
position  in  criticizing  the  separation  of  affection  from  sensa- 
tion —  that  affection  may  be  an  attribute  of  sensation  — 
meets  with  just  as  grave  difficulties.  As  Kiilpe  has  sug- 
gested, it  is  always  true  of  attributes  that  when  one  vanishes 
or  is  reduced  to  zero,  the  sensation  also  disappears.  Sensa- 
tions with  no  affective  tone  are,  on  the  contrary,  relatively 


AFFECTION  465 

common.  A  sensation  may  be  indifferent  and  still  be  a 
sensation,  while  a  sensation  that  has  no  quality  and  no 
intensity  ceases  to  exist.  Furthermore,  affections  have 
attributes  of  their  own  which  vary  independently  of  the 
attributes  of  sensation,  which  again  is  inconsistent  with  the 
assumption  that  affection  is  merely  an  attribute  of  sensa- 
tion. Affection  has  duration,  intensity,  and  quaHty,  is 
unpleasant  or  pleasant,  although  it  has  no  extent  or  posi- 
tion. On  the  affirmative  side  of  the  question,  it  must  be 
granted  that  we  apparently  never  have  affection  without 
some  sensation,  and  so  it  is  not  an  entirely  independent 
entity.  One  never  feels  vaguely  pleased  or  displeased: 
there  is  always  some  sensation  as  the  occasion  for  the  affec- 
tion. In  certain  instances  the  affection  seems  the  dominant 
element  in  consciousness,  but  slight  observation  indicates 
that  there  are  also  sensations,  usually  of  a  vague  organic 
character,  that  serve  as  the  excitant  of  the  feehng.  But, 
as  has  just  been  said,  this  same  sensation  may  at  times  be 
present  in  some  degree  without  any  accompanying  feehng 
or,  on  occasion,  with  a  feehng  of  the  opposite  character. 
On  the  whole,  it  seems  fairly  safe  to  conclude  that  the  quah- 
ties  of  pleasantness  and  unpleasantness  are  found  in  close 
dependence  upon  stimulus  and  sensation,  but  nevertheless 
constitute  what  may  be  regarded  as  an  independent  mental 
state,  or,  to  speak  more  conservatively,  as  a  phase  of 
consciousness  which  cannot  be  understood  if  we  regard  it 
as  merely  sensation,  or  as  an  attribute  of  sensation. 

Treating  our  topic  from  the  structural  point  of  view, 
affection  constitutes  a  type  of  mental  process  distinct  from 
sensation  but  nevertheless  dependent  for  its  existence  upon 
sensation,  certainly  upon  the  excitations  that  cause  sensa- 
tions. Pleasantness  and  unpleasantness  come  as  a  result 
of   sensory  excitation   immediate   or  recalled,   and   these 


466        FUNDAMENTALS  OF  PSYCHOLOGY 

excitations  produce  sensations  at  the  same  time  or  a  little 
before  they  give  rise  to  the  affections.  It  is  probably  true 
that  no  excitation  gives  rise  to  an  affection  without  also 
arousing  a  sensation.  The  occasional  periods  of  vague  well- 
being  or  vague  ill-being  without  apparent  sensational  basis 
are  rare,  and  in  all  probabiUty  are  merely  cases  in  which 
the  affective  aspect  of  consciousness  has  for  the  moment 
overshadowed  the  sensory.  While  affection  is  thus  depend- 
ent upon  the  same  excitations  as  sensations  and  even  prob- 
ably dependent  upon  the  sensations  themselves  for  its  exist- 
ence, it  is  not  a  mere  attribute  or  phase  of  the  sensation,  as 
are  quality  and  intensity;  rather  we  must  regard  it  as  a 
separate  mental  state  or  process  with  attributes  of  its  own. 
Qualities  of  Affection.  —  Starting  from  this  assumption, 
we  may  consider  affection  in  its  relation  to  the  various  stim- 
uli, enumerate  its  quahties  and  its  physiological  accompani- 
ments, in  much  the  same  way  as  we  have  treated  the  cog- 
nitive processes.  First,  with  reference  to  the  qualities  of 
feeling,  it  may  be  asserted  that  there  are  but  two,  pleasant- 
ness and  unpleasantness.  Many  objections  have  been 
raised  to  this  statement.  In  the  first  place,  as  has  been  seen, 
many  people  mean  altogether  different  kinds  of  mental 
processes,  intuitions  and  what  not,  from  those  that  we  have 
admitted  into  the  class.  These  we  may  exclude  by  mere 
arbitrary  definition.  They  certainly  have  a^  existence  and 
a  place  in  psychology,  but  fall  rather  under  reasoning  and 
other  heads  than  under  feeling.  They  simply  are  not 
sufficiently  Hke  the  processes  we  are  discussing  to  make  it 
possible  to  extend  the  term  to  include  them.  Wundt,  using 
the  term  in  somewhat  our  way,  makes  the  suggestion  that 
there  are  many  different  quahties  of  feeUng,  one  for  each 
sensation  and  intellectual  process.  To  this  the  majority 
of  psychologists  stand  in  direct  opposition.    The  differences 


AFFECTION  467 

that  strike  one  are  due  rather  to  the  quahties  of  the  accom- 
panying sensations  than  to  the  feeling  quahties  themselves. 
If  one  can  abstract  the  sensational  elements  from  a  feeling, 
the  purely  affective  remnant  is  always  the  same  —  pleasant 
or  unpleasant. 

Pleasantness  and  Unpleasantness  the  Only  Qualities  of 
Affection.  —  To  recognize  only  pleasantness  and  unpleas- 
antness as  quahties  of  affection  is  opposed  to  many  authori- 
ties, ancient  and  modern,  but  the  distinctions  they  draw 
seem  to  be  based  on  other  than  psychological  grounds. 
Thus,  the  morahst  of  everyday  hfe  draws  a  distinction 
between  higher  pleasures  and  lower  pleasures.  One  is  the 
pleasure  from  the  simple  senses,  the  pleasures  of  eating, 
for  example,  particularly  the  pleasures  from  the  satisfaction 
of  the  simpler  instincts,  while  the  higher  pleasures  are  the 
pleasures  of  the  imagination,  aesthetic  pleasures,  the  pleas- 
ures from  moral  acts.  In  general,  they  are  the  pleasures 
which  society  approves,  while  the  lower  pleasures  are  those 
which  are  either  disapproved  or  regarded  as  morally  in- 
different. This  distinction  is  recognized  by  every  one.  It 
is  at  the  basis  of  one  of  Dr.  Johnson's  favorite  distinctions 
between  pleasure  and  satisfaction.  Still  it  is  generally 
beheved  not  to  correspond  to  any  real  difference  in  psycho- 
logical quahty,  but  rather  to  a  distinction  based  upon 
ethical  considerations.  Sensuous  pleasure  is  beheved  to  be 
of  the  same  quahty  as  moral  pleasure;  the  pleasure  from  a 
pleasant  odor,  of  the  same  quahty  as  that  from  a  painting 
by  an  old  master.  The  difference  is  to  be  found  in  the  fact 
that  one  is  approved  by  the  connoisseur,  carries  with  it  a 
certificate  of  being  beyond  the  ken  of  the  multitude,  and 
takes  an  added  flavor  from  that  fact,  a  flavor  which  may 
intensify  the  other  quahty  but  is  of  the  same  general  class 
or  type.     Other  suggested  quahties  of  pleasant  and  un- 


468        FUNDAMENTALS   OF  PSYCHOLOGY 

pleasant  seem  on  analysis  to  reduce  to  similar  extraneous 
considerations  and  to  leave  but  two  qualities,  pleasantness 
and  unpleasantness.  In  general,  one  must  admit  with 
Wundt  that  the  total  feeling  varies  with  each  stimulation 
and  with  each  sensation  or  memory  or  other  sort  of  mental 
state;  however,  the  variation  is  not  in  the  affection  but  in 
the  sensational  accompaniments.  The  pleasantness  or  un- 
pleasantness is,  if  we  are  to  beUeve  the  introspections  of  the 
large  mass  of  psychologists,  always  identical;  and  the  dif- 
ferences that  Wundt  insists  upon  are  to  be  found  in  the 
cognitive  accompaniments.  The  differences  between  sen- 
suous, aesthetic,  and  moral  pleasures  or  displeasures  are  in 
the  occasions  of  the  affections,  in  the  cognitive  component  of 
the  feelings  rather  than  in  the  affective  elements  themselves. 

Other  Aspects  of  Feeling 

Other  Suggested  Pairs  of  Feelings.  —  Wundt  and  Royce 
assert  that  there  are  other  definite  opposites  of  consciousness 
that  must  also  be  classed  as  feehngs.  Royce  adds  two, 
restlessness  and  quiescence.  The  one  is  said  to  be  charac- 
terized by  a  constantly  changing  impulse  to  movement, 
particularly  by  a  feehng  that  one  must  get  on  to  do  some- 
thing else;  while  quiescence  implies  an  assent  to  the  present 
condition,  a  readiness  to  remain  in  the  condition  in  which 
one  is.  Wundt  affirms  that  there  are  three  pairs  of  affection 
which  may  be  regarded  as  constituting  a  three-dimensional 
series.  To  pleasantness-unpleasantness  he  adds  strain  and 
relaxation,  excitation  and  quiescence.  Strain  and  relaxa- 
tion are  related  to  the  feehng  of  effort  and  its  lack  in  atten- 
tion, —  strain  appears  in  expectation,  relaxation  in  realiza- 
tion. Wundt  insists  that  these  quahties  do  not  come  from 
the  contraction  of  the  muscles  and  their  relaxation,  but  are 
as  truly  affections  without  assignable  sense  organs  as  are 


OTHER   ASPECTS   OF   FEELING  469 

pleasantness  and  unpleasantness.  Excitation  arises  when 
one  is  disturbed  through  attempting  a  difficult  task,  is  a 
component  of  anger  and  of  certain  exhilarating  forms  of  joy. 
Quiescence  or  inhibition  is  an  accompaniment  of  rest,  per- 
haps of  lassitude.  They,  too,  are  pecuHar  qualities  of  affec- 
tion with  no  sense  organs  and  no  definite  relations  to  the 
other  forms  of  feeling.  These  extra  pairs  were  supposed  to 
be  accompanied  by  special  physical  reactions,  but  later 
investigators  seem  to  have  pretty  clear  evidence  that  the 
experiments  in  support  of  them  were  inaccurate  or  wrongly 
interpreted.  On  the  whole,  direct  observation  seems  not  to 
bear  out  Wundt's  contention  that  these  forms  of  conscious- 
ness are  feeHngs.  There  can  be  no  doubt  that  the  states 
exist,  but  they  seem  to  be  either  directly  due  to  special 
sensations  such  as  the  kin  aesthetic  impressions,  in  strain 
and  relaxation,  or  to  more  complicated  organic  processes  in 
excitation  and  quiescence.  These  are  probably  closely 
related  to  the  qualities  of  the  emotional  states  to  be  dis- 
cussed in  the  next  chapter.  In  any  case  they  are  not 
afifections  in  the  same  sense  as  'are  pleasantness  and  un- 
pleasantness. 

Intensity  of  Stimulus  and  Intensity  of  Affection.  —  The 
other  attributes  of  affection  call  for  but  brief  discussion. 
The  intensity  of  each  quality  of  affection  varies  from  zero 
to  a  maximum  that  may  end  in  the  loss  of  consciousness. 
The  relation  to  the  intensity  of  stimulus  has  been  expressed 
by  Wundt  in  a  curve  that  holds  for  stimuli  of  certain  kinds, 
although  there  may  be  exceptions.  A  faint  stimulus  is  usu- 
ally indifferent.  As  the  intensity  increases,  a  pleasant  affec- 
tion begins  and  increases  to  a  maximum  with  moderate 
excitations,  and  then  drops  to  indifference,  and  finally  be- 
comes unpleasant  as  the  excitation  is  increased  still  more. 
The  point  at  which  pleasantness  disappears  varies  with  the 


470        FUNDAMENTALS   OF  PSYCHOLOGY 

nature  of  the  stimulus.  In  many  cases  it  is  at  a  very  low 
point  in  the  scale  of  intensities;  for  other  qualities  all  but 
the  highest  intensities  are  pleasant.  With  suitable  allow- 
ances, practically  all  sense  quaHties  will  be  found  to  corre- 
spond with  the  rule  in  some  degree.  It  at  least  approxi- 
mates a  law.  In  the  diagram,  the  line  a  indicates  the 
increase  in  sensation  by  the  logarithmic  curve  in  accordance 
with  Weber's  law;   e,  the  curve  of  increase  in  intensity  of 


\ 


Fig.  03 .  —  Schematic  diagram  of  the  relation  of  affection  to  sensation.  The 
smooth  curve  shows  the  rise  of  sensation  with  intensity  of  stimulus,  the  dotted  line 
the  accompanying  rise  and  fall  of  pleasantness  and  the  increase  of  unpleasantness. 
(From  Wundt.) 

affection  —  above  the  Hne  indicating  pleasant,  below  the 
line  unpleasant  affection.  The  duration  of  affection  differs 
from  the  duration  of  the  stimulus  both  at  the  beginning  and 
the  end.  Affection,  as  has  been  said,  lags  behind  the 
stimulus,  appears  later,  a  little  after  the  sensation  even,  in 
most  cases,  and  may  either  disappear  before  the  stimulus 
or  change  its  tone  as  the  stimulus  persists.  Thus,  stimuli 
which  at  first  are  pleasant  may  become  indifferent  or  become 
unpleasant  if  they  last  too  long.  Duration  has  much  the 
same  tendency  as  intensity  in  this  respect,  and  one  might 


OTHER   ASPECTS   OF   FEELING  471 

draw  a  similar  curve.  The  tendency  is  always  for  the  feeling 
to  become  unpleasant  rather  than  pleasant  as  its  duration 
increases.  No  general  rule  can  be  given  even  for  the  same 
stimulus  as  to  how  great  the  duration  must  be  before  the 
quahty  will  change. 

Affection  and  the  Qualities  of  Sensation.  —  It  would  be 
highly  desirable,  were  it  possible,  to  give  either  a  catalogue 
or  some  general  law  that  should  classify  the  objects  or 
stimuli  that  give  rise  to  pleasure  or  displeasure.  We  have 
already  attempted  this  for  the  intensity  and  duration  of 
stimuli.  To  list  the  qualities  that  are  pleasant  is  much 
more  difficult.  Experimental  aesthetics  has  made  the  at- 
tempt in  certain  fields,  but  the  results  are  too  voluminous 
to  be  presented  in  detail,  and  the  general  summaries  are 
too  few  and  too  schematic  to  be  very  satisfactory. 

Bodily  Accompaniments  of  Feeling.  —  While  one  be- 
comes acquainted  with  feeling  primarily  through  inner  ob- 
servation or  introspection,  numerous  attempts  have  been 
made  to  obtain  some  record  of  the  behavior  in  feeling  that 
may  serve  as  a  measure  of  the  amount  of  feeling,  or  even 
as  an  indication  of  the  nature  of  feeling.  It  is  a  matter  of 
common  observation  that  practically  all  individuals  show 
pleasure  or  displeasure  by  certain  physical  changes.  The 
face  is  said  to  light  up  or  to  lower,  and  the  general  bodily 
attitude  changes  in  accordance  with  the  feelings.  In  most 
cases  the  presence  of  pleasure  or  its  opposite  can  be  read- 
ily and  clearly  detected  by  observation.  Many  investiga- 
tions have  been  undertaken  and  carried  out  to  translate 
these  simple  observations  into  more  accurate  measure- 
ments. One  of  the  first  series  of  studies  was  of  the  changes 
in  respiration  and  circulation.  The  first  results  seemed  to 
indicate  that  there  was  a  definite  opposition  in  these  pro- 
cesses corresponding  to  the  opposition  between  pleasant- 


472        FUNDAMENTALS   OF  PSYCHOLOGY 

ness  and  unpleasantness.  Thus  Lehmann  ^  asserts  that  in 
pleasure  respiration  is  slow  and  deep;  while  in  unpleasant- 
ness, at  least  after  an  initial  inhibition,  it  is  quick  and 
shallow.  The  pulse,  similarly,  is  said  to  be  slow  and  strong 
in  pleasure,  and  quick  and  weak  in  unpleasantness;  the 
blood  vessels  dilate  in  pleasure,  contract  in  unpleasantness. 
Later  investigations  by  Courtier, ^  Shepard,^  and  others 
make  it  quite  clear  that  the  effects  depend  very  largely 
upon  the  strength  of  the  stimuli  rather  than  upon  the  af- 
fective tone;  that  all  stimuli  tend  to  quicken  the  respira- 
tion and  make  it  shallow,  to  quicken  the  pulse  and  make  it 
feeble,  and  to  constrict  the  blood  vessels.  It  is  altogether 
probable  that  Lehmann's  results  with  pleasure  were  due  to 
the  fact  that  pleasant  stimuli  are  usually  faint,  and  so  if 
there  has  been  strong  stimulation  just  before,  the  vital 
processes  tend  to  return  to  normal,  and  thus  seem  to  show 
changes  that  are  the  reverse  of  the  effects  of  the  stimula- 
tion. Wundt  and  his  students  have  attempted  to  demon- 
strate peculiar  physiological  changes  of  the  same  sort  in 
connection  with  his  suggested  pairs  of  strain  and  relaxa- 
tion, exaltation  and  depression;  but  study  of  their  curves 
indicates  that  they  have  been  misled  by  similar  phenomena 
of  recovery,  and  by  rhythmic  changes  that  have  no  rela- 
tion to  the  changes  in  the  feeHng  that  they  are  studying. 

Other  Physiological  Changes.  —  Of  the  other  physio- 
logical changes  in  connection  with  feeHng,  the  secretion  of 
saHva  has  been  studied  most  extensively  by  Pawlow.  He 
found  that  it  was  possible  to  record  from  the  study  of  the 
dog  many  of  the  changes  that  result  from  stimulations 
which  in  man  are  accompanied  by  feeling  and  even  by  in- 

'  Lehmann,  Hauptgesetze  d.  menschlichen  Gefiihlsleben. 

^  Courtier,  L'Annee  psychologique.  Vol.  i. 

^  Shepard,  American  Journal  of  Psychology,  Vol.  17. 


OTHER   ASPECTS   OF   FEELING  473 

tellectual  processes.  This  he  accomplished  by  dissecting 
out  the  duct  of  the  salivary  gland  in  the  cheek  of  the  dog, 
and  adjusting  it  so  that  the  saliva  might  flow  into  the  pan 
of  a  recording  scale.  It  was  found  that  the  sight  of  food  or 
of  any  object  associated  with  food  led  to  an  increased  flow, 
and  that  the  amount  secreted  was  a  very  good  indication 
of  the  mental  state  of  the  dog.  This  corresponds  to  the 
dryness  of  the  mouth  in  man  in  displeasure  or  excitement, 
particularly  in  fear,  and  the  free  flow  of  saliva  in  pleasure 
even  when  that  be  not  associated  with  food.  The  opposi- 
tion between  pleasantness  and  unpleasantness  does  not 
hold  altogether  here,  again,  since  any  strong  excitement, 
pleasant  or  unpleasant,  gives  the  same  dry  mouth. 

Somewhat  the  same  statement  may  be  made  of  the  se- 
cretion of  tears.  Strong  grief  or  displeasure  causes  weep- 
ing, but  the  brightness  of  the  eye  in  pleasure  is  also  due  to 
increased  secretion  of  the  lachrymal  gland  which  in  ex- 
treme pleasure  may  overtax  the  tear  ducts  and  flow  down 
the  cheek. 

Slightly  better  evidence  may  be  given  for  an  opposition 
in  expression  in  the  bodily  posture.  Grief  seems  to  be 
marked  by  a  drawing  together  of  all  the  members,  while 
pleasure  leads  to  an  actual  physical  expansion,  —  head 
erect,  even  thrown  back  as  in  laughter,  the  arms  extended 
and  the  trunk  held  straight.  These  general  bodily  move- 
ments have  been  much  less  carefully  studied  than  the 
others,  and  the  opposition  of  the  dift'erent  kinds  of  feeUngs 
shown  in  superficial  observations  may  disappear  upon  fuller 
investigation. 

We  may  assert,  then,  that  the  feelings  show  very  marked 
bodily  accompaniments,  but  that  these  cannot  be  said  to 
correspond  accurately  to  the  differences  between  pleasant- 
ness and  unpleasantness,  although  the  degree  of  our  feeling 


474        FUNDAMENTALS   OF  PSYCHOLOGY 

carries  with  it  an  approximately  corresponding  amount  or 
intensity  in  the  accompanying  physical  expression.  The 
expression  of  the  feelings  merges  gradually  into  emotional 
expression,  which  must  form  a  considerable  portion  of  the 
matter  of  the  next  chapter. 

Theories  of  Feeling 

Difficulties  in  Formulating  a   Theory  of   Feeling.  —  In 

attempting  to  summarize  the  facts  collected  concerning 
feeUng  and  to  refer  them  to  a  single  principle,  many  the- 
ories have  been  developed.  At  present  the  facts  cannot  be 
brought  to  harmonize  with  any  single  general  statement; 
but,  rather,  different  groups  of  facts  may  be  brought  to 
the  support  of  different  statements  in  themselves  not  alto- 
gether consistent.  While  no  single  theory  may  be  said  to 
be  true  to  the  exclusion  of  the  others,  all  taken  together 
give  a  better  idea  of  the  nature  of  feehng  and  its  relations 
than  can  be  obtained  by  any  mere  statement  of  facts.  The 
first  element  that  is  lacking  in  the  construction  of  a  theory 
is  a  satisfactory  basis  in  the  nervous  system.  Each  of  the 
other  fundamental  processes  has  a  definite  nervous  struc- 
ture or  activity  to  which  it  may  be  referred,  and  which 
gives  definiteness  to  the  explanation;  but  affection  has 
neither  special  sensory  nerves  to  provide  it  a  particular 
stimulus,  nor  special  central  structures  that  elaborate  its 
materials.  Study  of  pathological  cases  of  disturbances  of 
the  affective  life  in  the  symptoms  of  melancholia  or  eu- 
phoria are  accompanied,  so  far  as  at  present  known,  by 
no  peculiar  lesions  with  which  the  diseased  affections  may 
be  associated  or  to  which  they  may  be  referred.  So  far  as 
changes  in  the  nerve  tissue  have  been  traced,  they  are 
widespread  and  general  rather  than  closely  localized  and 
specific.    It  cannot  be  said  that  one  is  pleased  or  displeased 


THEORIES   OF   FEELING  475 

in  any  particular  part  of  the  brain  or  nervous  system,  or 
that  affection  is  carried  by  any  particular  nerve  or  corre- 
sponds to  any  peculiar  jirocess. 

Physiological  Theories.  —  Of  the  theories,  we  may  dis- 
tinguish three  main  groups  with  several  cross  hues  of  divi- 
sion. One  of  the  oldest  and  most  generally  accepted  makes 
pleasure  and  displeasure  the  accompaniment  and  indication 
of  benefit  and  injury  to  the  organism.  This  takes  different 
forms,  either  as  an  expression  of  an  immediate  change  in 
the  organism  in  general,  of  the  nervous  system  as  a  whole, 
or  of  some  particular  part  of  the  nervous  system.  It  may 
be  an  indication  of  what  has  been  good  or  bad  for  the  in- 
dividual or  race  in  the  past  and  is  likely  to  prove  so  in  the 
future.  For  these  theories,  pleasure  means  that  there  is  in 
the  individual,  at  the  moment  a  process  of  upbuilding,  of 
anaboUsm;  that  this  anabolism  is  induced  in  the  nervous 
system  as  a  whole  or  in  the  frontal  lobe,  — ■  for  Wundt  the 
great  coordinating  centre  for  all  nervous  and  mental  activ- 
ity. The  evidence  for  each  of  these  theories  is  indirect  and 
may  be  found  in  the  general  law  that  the  beneficial  is  on 
the  whole  pleasant,  that  the  injurious  is  on  the  whole  un- 
pleasant. Correspondingly,  when  one  is  physically  in  good 
health,  well  rested  and  nourished,  many  activities  and  even 
excitations  are  pleasant  which  become  unpleasant  when 
the  physical  tone  is  lower.  These  facts  have  been  inter- 
preted to  mean  that  action  of  a  well-nourished  nervous 
system  or  part  of  the  nervous  system  means  pleasure,  and 
that  the  action  of  a  badly  nourished  system  means  dis- 
pleasure. Taken  hterally,  the  identification  of  pleasure 
with  anaboHsm,  and  displeasure  with  kataboHsm,  would 
make  all  action  and  stimulation  unpleasant,  since  all  ac- 
tion involves  use  of  reserve  nutriment.  The  anabohsm- 
katabolism  formula  has  been  modified  by  permitting  kata- 


476        FUNDAMENTALS   OF  PSYCHOLOGY 

holism  within  moderate  limits,  the  limits  of  ready  recuper- 
ation, to  give  pleasure.  This  limit  would  be  difficult  to 
determine  empirically,  however. 

Evolutionary  Theory.  —  Another  change  in  the  state- 
ment of  the  theory  permits  the  formula  to  mean  a  general 
benefit  or  injury  to  the  race  in  the  evolutionary  sense. 
This  enables  one  to  account  for  many  of  the  seeming  dis- 
crepancies between  benefit  and  pleasure.  Thus,  it  seems  at 
first  not  true,  even  in  general,  that  the  pleasant  in  food  or 
drink  is  also  beneficial.  Aside  from  exceptions,  however,  we 
do  use  feehng  as  a  guide  to  foods.  We  eat  what  we  like,  or 
at  least  we  do  not  eat  what  we  do  not  hke.  The  excep- 
tions apply  to  excesses  or  to  substances  of  rare  -occurrence 
in  the  environment  in  which  the  race  evolved.  The  race 
as  a  whole  is  more  likely  to  survive  if  it  makes  use  of 
pleasant  but  injurious  foods,  such  as  sweet  poisons,  than 
if  it  ate  no  sweets.  The  exceptions  must  be  learned  by  in- 
dividual experience.  It  is  much  better  to  eat  than  not  to 
eat,  in  spite  of  the  fact  that  overeating  is  harmful.  When 
to  stop  can  be  learned  from  the  unpleasant  symptoms  that 
indicate  injury.  Pleasantness  and  unpleasantness  serve  as 
a  general  guide  to  conduct,  and  may  be  said,  metaphori- 
cally, to  be  the  expression  in  the  individual  of  the  experi- 
ence of  the  race  as  to  what  is  good  or  bad.  This  expression 
is  open  to  many  exceptions,  is  not  a  final  law,  but  must  be 
modified  by  the  experience  of  the  individual  and  the  accu- 
mulated knowledge  of  the  race.  It  should  be  added  that 
the  manner  in  which  the  experience  is  recorded  and  trans- 
mitted in  the  individual,  and  how  and  why  it  acts,  are  not 
at  all  known.  The  theory  is  nothing  more  than  a  formu- 
lation of  the  general  group  of  facts  that,  in  the  long  run, 
what  pleases,  benefits;  what  displeases,  harms. 

Furtherance-Hindrance  Theories.  —  Another   group    of 


THEORIES   OF   FEELING  477 

theories  accounts  for  the  more  active  pleasures  largely 
overlooked  in  the  theories  just  mentioned.  This  group 
couples  easy  running  or  unopposed  action  with  pleasure, 
difficult  or  opposed  action  with  displeasure.  In  one  form 
the  theory  makes  real  physical  movements  the  basis,  in 
other  groups  it  is  taken  in  a  more  metaphorical  sense. 
Thus,  the  first  theory  states  that  a  smooth,  graceful  curve 
is  pleasant  because  the  eye  will  follow  it  without  effort, 
with  a  single  sweep;  while  a  series  of  short  lines  with 
many  changes  in  direction  is  ugly  because  of  the  difficulty 
of  the  eyes  in  following  them. 

A  shght  departure  toward  the  metaphorical  is  seen  in 
the  theory  of  'empathy'  (Einfuhlung)  of  Lipps,  in  which 
the  individual  does  not  necessarily  have  opposed  action  in 
his  own  body,  but  sympathizes  with  the  figure,  feels  in  un- 
pleasantness that  he  would  have  difficulty  in  doing  what 
he  personifies  the  figure  as  doing. 

Finally,  we  have  Stout's  theory  that  one  may  have  op- 
position in  the  accomplishment  of  an  intellectual  purpose, 
in  reaching  some  conclusion  in  thought;  or,  on  the  con- 
trary, one's  mental  operations  may  run  smoothly  or  be 
helped,  and  so  be  pleasant.  In  each  of  these  cases  further- 
ance or  easy  action  means  pleasure,  hindrance  or  inter- 
rupted action  displeasure.  As  before,  one  may  accept  the 
general  statement,  particularly  in  the  metaphorical  form, 
although  the  more  specific  applications  offer  much  room 
for  doubt  and  may  be  disputed  as  to  facts. 

Feelings  Dependent  upon  Earlier  Experiences.  —  The 
third  form  of  theory  attempts  to  explain  how  feeUng  can 
be  dependent  upon  such  a  wide  range  of  experiences, 
rather  than  why  one  is  pleased  or  displeased.  The  first 
form  of  this  theory  is  Wundt's  statement  that  feeUng  is 
the  obverse  of,  or  at  least  one  phase  of,  apperception.    For 


478        FUNDAMENTALS   OF  PSYCHOLOGY 

Wundt,  apperception  is  practically  synonymous  with  the 
active  life,  covers  much  of  what  is  treated  under  atten- 
tion, perception,  and  will.  It  is  the  effect  of  the  entire 
earher  experience  of  the  individual  in  the  control  of  his 
present  action  in  attending,  in  interpreting  the  material 
offered  to  perception,  in  thought,  and  in  practical  conduct. 
This  definition  makes  feehng  an  expression  of  the  interac- 
tion between  the  coordinated  earlier  experience  of  the  in- 
dividual and  the  present  experience.  On  the  nervous  side, 
Wundt  gives  apperception  a  seat  in  the  frontal  lobe,  prob- 
ably in  the  front  portion  of  the  frontal  lobe,  and  so  com- 
bines his  psychological  theory  with  the  physiological  in 
the  formula  mentioned  above,  that  pleasure  corresponds 
to  the  action  of  a  well  nourished,  displeasure  to  the  action 
of  a  badly  nourished,  frontal  lobe.  This  means,  or  may  be 
made  to  mean,  that  whether  any  process  is  pleasant  or  un- 
pleasant depends  upon  the  entire  accumulated  experience 
of  the  individual  and  in  the  way  that  experience  is  brought 
to  bear  upon  the  process  in  question,  a  statement  that  is 
undoubtedly  true,  although  somewhat  vague.  If  we  re- 
place apperception  by  attention,  and  consider  the  nervous 
factors  that  are  found  to  determine  the  control  of  attention, 
we  should  have  approximately  the  same  formula  in  our 
own  terms. 

Summary.  —  We  may  assert  that  feeling  is  an  expression 
of  the  factors  that  control  attention,  an  expression  of  the 
interaction  between  the  instincts  and  past  experience  of 
the  individual,  and  the  present  situation.  It  is  an  indica- 
tion of  the  reaction  of  the  nervous  system  of  the  individual, 
as  the  result  of  original  endowment  and  individual  acquire- 
ment, to  the  stimuli  of  the  moment.  To  give  an  explana- 
tion of  pleasantness  and  unpleasantness  this  formula  would 
need  to  consider  the  essential  phases  of  the  other  two 


THEORIES   OF   FEELING  479 

theories.  The  theories  are  mutually  complementary  rather 
than  exclusive.  Thus,  the  pecuhar  reactions  that  give 
rise  to  pleasure  are  indications  that  the  stimuli  in  question 
have  been  beneficial;  those  that  give  rise  to  displeasure 
have  been  on  the  whole  injurious,  either  to  the  race  or  to 
the  individual.  In  the  one  case  we  deal  with  an  instinctive 
response,  in  the  other  with  a  response  due  to  individual 
acquirement.  In  the  individual  acquirement,  association 
with  similar  experiences  or  direct  connection  with  other 
experiences,  either  in  themselves  unpleasant  or  pleasant, 
plays  a  large  part.  One  may  have  the  affection  of  the 
associated  event  without  having  the  event  itself  definitely 
recalled,  as  can  be  seen  in  the  dislike  of  many  foods  with 
which  one  has  had  unpleasant  experiences,  or  a  liking  for 
colors  that  have  been  connected  with  some  very  pleasant 
occasion.  The  feeling  comes,  in  such  cases,  without  nec- 
essarily recalling  the  event  that  may  reasonably  be  supposed 
to  have  occasioned  it.  Just  what  the  nature  of  the  re- 
action may  be  that  gives  rise  to  feehng,  why  we  become 
conscious  in  feeling  of  the  nature  of  the  forces  that  are 
active  in  controlling  attention,  we  cannot  at  present  say. 
The  justification  for  the  theory  is  the  far-reaching  de- 
pendence of  feelings  upon  so  much  of  the  earlier  Hfe  of  the 
individual. 

REFERENCES 

Titchener:  Psychology  of  Feeling  and  Attention. 
Marshall:  Pain,  Pleasure,  and  Esthetics. 
Warren:  Human  Psychology,  pp.  279-286. 


CHAPTER  XVI 

EMOTION  AND   TEMPERAMENT 

Probably  the  most  impelling  and  self-asserting  mental 
state  of  all  is  emotion.  For  good  or  for  ill  it  marks  the 
greatest  disturbance  in  the  course  of  mental  events,  and  is 
the  most  personal,  the  most  pervasive.  Emotions  stand 
in  closest  connection  with  feeling  and  with  instinct.  From 
the  feelings  they  can  be  distinguished  only  by  the  amount  of 
response  that  accompanies  them  and  by  their  general  com- 
plexity. Unpleasantness  becomes  anger  or  fear  when 
movements  of  attack  or  flight  begin,  when  the  muscles  of 
the  face  and  of  the  internal  organs  grow  tense,  and  give 
rise  to  sensations.  On  the  other  hand,  many  of  the  occasions 
for  the  emotions  and  practically  all  of  the  movements  ac- 
companying emotion  are  instinctive.  Emotion  may  be 
defined  by  virtue  of  these  relationships  either  as  a  com- 
plicated feeling  or  as  the  subjective  side  of  the  instinct. 
The  list  of  emotions  ordinarily  given  has  varied  relatively 
little  since  Descartes,  and  his  list  can  be  traced  with  com- 
paratively few  changes  to  much  earlier  periods.  His  list 
includes:  surprise,  love  and  hate,  desire,  pleasure  and  dis- 
pleasure; while  in  Shand,  one  of  the  latest  writers  who 
has  elaborated  upon  the  classification,  we  find :  fear,  anger, 
joy,  sorrow,  disgust,  wonder,  to  which  McDougall  adds 
the  more  personal  qualities  of  dejection  and  elation.  These 
are  for  all  authorities  the  more  fundamental  emotions. 
The  others  develop  from  them  by  combination,  by  change 
in  intensity,  in  the  nature  of  the  object  that  arouses  them, 
480 


CHARACTERISTICS   OF   EMOTION         481 

or  in  the  time  at  which  the  event  that  arouses  the  emotion 
has  occurred  or  is  to  occur. 

Characteristics  of  Emotion 
Classifications  of  the  Emotions.  —  In  any  discussion  of 
the  emotions  it  is  essential  to  consider  separately  two 
factors:  the  conditions  or  causes  of  the  emotions,  and  the 
mental  content  and  physical  reaction  during  the  emotion. 
There  are  two  possible  classifications  of  emotions  with 
reference  to  cause,  although  the  cause  does  not  necessarily 
affect  the  quality  of  the  emotions.  Two  general  causes 
for  emotions  have  been  assigned.  One,  generally  current 
at  present,  asserts  that  emotion  is  merely  an  instinct  seen 
from  the  inside,  that  the  real  cause  is  to  be  found  in  the 
instinctive  response.  The  other,  which  goes  back  to  re- 
mote antiquity,  insists  that  emotions  arise  from  some  con- 
flict between  ideals  or  desires  and  the  momentary  environ- 
ment. The  first  theory  appUes  best  to  those  emotions  called 
out  immediately  by  some  external  stimulus  by  virtue  of  a 
fundamental  characteristic  of  the  organism.  Sudden  fear 
at  sight  of  a  snake,  sudden  anger  at  an  injury,  the  sudden 
glow  of  love  at  first  sight,  all  fall  in  this  class.  They  need 
no  explanation  other  than  the  inherited  nervous  mechanism. 
The  second  group  of  theories  finds  its  explanation  in  the 
checking  of  some  general  movement  or  current  in  the  life 
of  the  individual.  In  the  writings  of  the  older  men  one 
finds  much  difference  of  opinion  as  to  what  it  was  that 
moved,  but  they  agree  that  all  emotions  arise  from  a  check- 
ing or  facihtation  of  the  movement,  and  also  that  unpleasant 
emotions  arise  from  the  checking,  pleasant  emotions 
from  the  facilitation.  For  Descartes  the  obstruction  was 
suffered  by  the  movements  of  the  fluid  products  of  digestion 
or  the  blood ;  for  Spinoza  the  movement  was  of  an  unnamed 


482        FUNDAMENTALS   OF  PSYCHOLOGY 

mental  force  which  was  pressing  towards  a  goal  of  hypo- 
thetical perfection.  For  Shand  the  impelling  force  is  what 
he  calls  sentiment,  a  force  derived  in  part  from  instinct, 
in  part  from  experience,  and  in  part,  perhaps,  underived, 
which  exhibits  systems  or  groups  of  forces  in  ever-widening 
subordinations.  These  he  divides  into  the  three  classes: 
love,  parental  sentiment,  and  the  unselfish  or  social  senti- 
ment. When  these  sentiments  find  free  play  or  are  assisted, 
pleasant  emotions  are  experienced;  when  checked  or 
thwarted  in  any  way  the  emotion  is  unpleasant.  "Every 
primary  impulse  .  .  .  when  opposed  tends  to  arouse  anger ; 
when  satisfied,  joy;  when  frustrated,  sorrow;  and  when 
it  anticipates  frustration,  fear." 

The  System  of  Purposes  in  Emotion.  —  If  one  is  to 
accept  at  all  this  old  theory,  obviously  the  first  problem 
is  to  determine  what  it  is  that  gives  rise  to  the  determining 
impulse  or  sentiment,  or,  in  a  more  conscious  sense,  the 
goal  of  action.  As  was  seen  in  an  earlier  chapter,  instinct 
suppHes  the  impelfing  force,  the  directing  influence,  in  most 
conscious  processes.  To  instinct  are  due  the  fundamental 
tendencies.  But  upon  them  is  built  a  great  superstructure 
of  desires,  acquired  from  education,  through  Hving  in  a 
particular  environment,  which  serves  to  differentiate  the 
aims  of  the  individual  from  his  fellows,  and  characterizes 
the  ideals  of  the  people  of  one  community  or,  social  stratum 
or  of  one  country  or  of  one  race.  The  last  two  mentioned 
are  dependent  in  part  upon  social  instincts  which  make  the 
suggestions  and  the  aims  of  the  group  acceptable  to  the 
individual.  The  traits  common  to  all  are  instinctive; 
the  more  particular  result  from  education.  Granted  that 
it  is  instinctive  to  attain  wealth,  one  must  admit  that  the 
form  that  wealth  is  to  take  varies  from  race  to  race,  and  the 
amount  aimed  at  is  different  for  different  social  groups 


CHARACTERISTICS   OF   EMOTION         483 

within  the  community.  Whether  one  strives  for  the  wam- 
pum or  cattle  of  the  savage,  as  opposed  to  the  bank  ac- 
count of  modern  man,  is  a  question  of  environment;  as  is 
also  whether  one  sets  one's  goal  at  milhons  or  thousands. 
Similarly,  desire  for  social  approval,  for  what  may  be 
called  fame,  is  general,  perhaps  instinctive,  but  whether 
in  athletic  skill  or  scholarship,  whether  in  business  or  in 
art,  in  poUtics  or  war,  depends  upon  early  environment 
and  even  upon  chance  factors  in  education.  Both  the 
sentiments  and  impulses  of  instinctive  origin  and  the 
ambitions  developed  at  the  more  conscious  stage  must  be 
assumed,  if  emotion  is  to  exist.  '  An  individual  to  whom 
nothing  really  mattered  would  be  without  emotion.  The 
presence  of  a  system  of  aims  makes  possible  the  bare 
potentiaUty  of  emotion;  the  nature  of  the  aim  determines 
the  character  of  the  objects  that  shall  excite  the  emotions. 
The  emotion  itself  is  an  incident  in  the  struggle  for  the 
attainment  of  an  end. 

The  Qualities  of  Emotion.  —  While  one  may  distinguish 
two  classes  of  emotion  from  the  standpoint  of  instinctive 
purposes  which  are  furthered  or  thwarted,  no  corresponding 
difference  can  be  discovered  in  the  quahties  of  emotion. 
From  comparing  the  qualities  of  the  results,  it  is  impossible 
to  say  whether  anger  has  been  produced  by  a  sudden  swift 
reaction  to  an  act  of  brutahty  towards  yourself  or  another, 
or  whether  it  is  the  result  of  being  thwarted  in  a  long- 
cherished  ambition.  The  exultation  over  obtaining  the 
means  of  satisfying  a  long-continued  hunger  is  not  difTerent 
from  the  exultation  over  winning  an  academic  honor. 
No  distinction  in  quality  can  be  made  between  emotions, 
however  different  may  be  their  conditions  or  origin. 

Recent  discussion  has  revolved  more  about  the  quahties 
of  the  emotion  than  the  occasion  upon  which  the  qualities 


484        FUNDAMENTALS  OF  PSYCHOLOGY 

depend.  The  descriptions  and  explanations  savor  much  of 
ancient  theories.  These  had  much  to  say  about  the  part 
of  the  body  that  was  active  in  the  emotion  and  were  very 
full  in  their  descriptions  of  the  accompanying  physical 
states.  Thus,  Plato  assigned  courage,  ambition,  and  the 
nobler  emotions,  to  the  heart;  while  lust  and  the  baser 
passions  had  their  seat  below  the  diaphragm.  In  common 
observation  one  may  find  the  explanation  of  these  references 
in  the  sensations  derived  from  the  general  region  of  the  body 
in  which  the  movements  are  felt.  The  changes  in  rate  of 
breathing,  in  the  circulation,  contractions  of  the  muscles 
of  the  chest  and  abdomen,  all  are  noted  by  the  chance 
observer  and  are  prominent  in  the  novehst's  descriptions 
of  mental  states.  While  the  modern  author  no  longer 
ascribes  the  emotions  to  the  internal  organs  in  the  same 
sense  as  did  the  ancients,  he  still  looks  to  the  organic  sensa- 
tions for  the  coloring  of  the  emotions;  in  fact,  for  a  quarter 
of  a  century,  psychologists  have  been  engaged  in  a  contro- 
versy as  to  whether  these  organic  changes  do  or  do  not 
explain  both  the  origin  and  the  content  of  emotion. 

The  James-Lange  Theory.  —  This  controversy  began 
with  and  has  revolved  about  a  theory  propounded  simul- 
taneously by  Lange  and  James.  The  theory,  stated 
briefly,  is  that  the  movements  of  the  body,  when  felt,  are 
the  emotion;  and  that  the  mental  factors'  are  altogether 
subordinate.  James  states  it  in  the  apparent  paradox 
that  you  are  sad  because  you  weep,  rather  than  weep  be- 
cause you  are  sad.  He  enumerates  a  number  of  cases  in 
which  the  emotion  comes  only  after  the  movements  have 
been  felt.  One  may  face  a  situation  with  no  great  appre- 
ciation of  its  danger,  even  with  knowledge  that  it  is  not 
dangerous,  and  suddenly  become  aware  of  a  trembhng, 
together  with  a  sinking  feeling  in  the  abdomen;   with  this 


CHARACTERISTICS   OF   EMOTION         485 

movement  the  emotion  of  fear  is  fully  established.  One 
may  look  over  a  cliff  with  perfect  confidence  of  safety,  and 
then  suddenly  feel  a  dizziness  and  trembhng  that  destroys 
one's  self-assurance  and  even  compels  one  to  draw  back 
involuntarily.  In  these  cases  action  and  thought  seem  to 
be  at  variance,  and  action  takes  precedence  over  thought. 
The  theory  in  general  must  be  accepted  as  at  least  a  rough 
statement  of  certain  facts,  and  this  makes  it  necessary  to 
examine  carefully  the  opposing  arguments. 

Obviously  the  problem  revolves  about  the  possibility 
of  discovering  instances  in  which  emotions  disappear  with 
loss  of  organic  sensations,  and  instances  in  which  the 
bodily  reactions  occur  and  give  rise  to  emotion  when  the 
ordinary  conditions  of  emotion  are  absent.  The  first 
condition  was  fulfilled  by  certain  hysterical  patients  who 
were  completely  anaesthetic  in  both  internal  organs  and 
external  muscles.  Several  of  these  were  questioned  in  the 
interests  of  the  theory.  The  reports  agree  in  general  that 
complete  anaesthesia  in  the  parts  usually  involved  in  the 
emotions  is  accompanied  by  loss  of  emotion.  One  patient, 
a  man  who  had  always  been  normally  emotional,  suddenly 
lost  all  sensitivity,  and  immediately  thereafter  became 
absolutely  indifferent  to  all  that  passed  about  him.  He 
parted  from  his  wife,  of  whom  he  was  very  fond,  without 
any  feeUng  of  sorrow,  and  his  reactions  to  experiences  that 
had  previously  been  strongly  toned  suddenly  became 
neutral  or  were  lacking  altogether.  While  the  fact  is 
generally  accepted,  Sollier^  has  questioned  whether  the 
loss  of  emotion  is  due  to  the  disappearance  of  sensation 
or  to  the  general  reduction  in  the  cortical  tone  in  hysteria. 
Hysterical  patients  also  suffer  diminution  of  all  the  higher 
psychical  functions,  so  that  it  is  not  at  all  surprising  that 
^  Sollier,  Le  mecanisme  des  emotions. 


486        FUNDAMENTALS   OF  PSYCHOLOGY 

their  ability  to  appreciate  the  experience  in  a  way  to  arouse 
emotions  should  be  lost.  In  this  case  the  failure  to  have 
emotions  would  be  due  to  the  intellectual  defects  or  to 
defects  in  the  higher  cortical  centres  rather  than  to  the 
mere  failure  to  feel  responses. 

Almost  as  contradictory  results  were  obtained  from  a 
study  of  actors  who  were  questioned  on  the  supposition 
that  they  would  provide  instances  in  which  the  emotion 
would  be  felt  when  the  movements  were  made  without  any 
real  occasion  for  the  response.  A  number  of  famous  actors 
and  actresses  were  asked  whether  they  felt  the  emotions 
that  they  depicted.  The  answers  showed  that  they  were 
divided  into  two  groups:  those  who  really  felt  what  they 
were  portraying,  and  a  second  group  who  merely  carried 
through  their  parts  as  machines.  Some  asserted  that  they 
felt  after  a  performance  as  if  they  had  actually  experienced 
the  events  of  the  play  and  felt  during  the  performance  as 
keenly  as  if  the  scenes  were  real;  the  others  were  perfectly 
cold.  No  definite  division  could  be  made  between  the  groups 
on  the  basis  of  distinction  or  success;  it  seems  merely  that 
one  group  conforms  to  the  demands  of  the  theory,  the  other 
does  not.  James  asserts  that  one  must  assume  that  in  one 
group  only  the  external  muscles,  the  muscles  of  the  face  and 
those  that  give  the  bodily  postures,  are  affected,  while  the 
deeper-lying  reactions  are  lacking.  It  would  seem  from 
this  that  the  sensations  essential  to  the  complete  emotional 
experience  come  from  the  activity  of  the  internal  organs. 
The  others  are  at  least  less  important. 

In  any  discussion  of  this  theory  a  sharp  line  must  be 
drawn  between  the  condition  of  an  emotion  and  its  qualities. 
James  assumes  the  movements  and  raises  no  questions  as 
to  how  they  are  excited.  He  takes  them  for  granted  as 
fundamental  reactions  of  the  nervous  system.    He  is  con- 


BODILY   RESPONSES    IN   EMOTION        487 

tent  in  his  detailed  discussion  to  show  that  the  emotion 
as  we  feel  it  is  nothing  more  than  the  awareness  of  the 
bodily  state;  he  makes  no  attempt  to  say  what  causes 
the  reaction  itself.  He  asks  only  whether  anything  other 
than  the  movements  can  contribute  to  the  emotional 
experience.  Granting  that  this  in  the  main  must  be 
answered  in  the  affirmative,  much  further  investigation 
remains  ahead  of  us. 

It  is  to  be  noted  in  James'  discussion  that  he  does  not 
specify  with  great  accuracy  what  the  movements  in  any 
particular  emotion  may  be.  He  is  content  to  assert  that 
there  are  movements,  and  to  prove  that  these  constitute 
the  quahty  of  the  emotion.  In  this  most  of  his  disciples 
have  followed  him.  They  speak  much  of  strains,  sinking 
feeHngs,  and  the  like,  but  no  single  emotion  is  distinctly 
described  and  distinguished  from  others  on  the  basis  of  its 
bodily  accompaniments.  For  attempts  at  these  details 
one  must  turn  to  recent  investigations  in  physiology. 

Bodily  Responses  in  Emotion 

The  Sympathetic  System  in  Emotion.  —  Cannon  ^  and 
his  students  and  Sherrington  have  made  experiments 
which  show  what  some  of  the  changes  are  and  what  part 
they  play  in  the  emotion.  Cannon  asked  two  questions: 
I.  What  are  the  bodily  responses  in  fear,  anger,  and 
general  excitement?  and  2.  What  is  the  value  of  these 
responses  to  the  organism?  For  an  answer  to  the  first 
question  he  looked  to  demonstrable  organic  responses. 
In  general,  emotions  were  found  to  spread  through  the 
sympathetic  system  to  practically  all  of  the  abdominal 
organs.  Pawlow  had  shown  that  the  flow  of  saliva  and 
the  secretion  of  the  digestive  fluids  in  the  stomach  were 

1  Bodily  Changes  in  Pain,  Hunger,  Fear,  and  Rage. 


488        FUNDAMENTALS   OF  PSYCHOLOGY 

increased  by  the  taste  or  odor  of  pleasant  foods,  even  by- 
sights  or  sounds  that  had  been  associated  with  such  foods. 
It  has  also  been  shown  that  pain  or  the  emotions  excited 
in  a  dog  by  the  sight  of  a  cat  or  in  a  cat  by  the  attempted 
attack  of  a  dog  served  to  check  the  flow  of  these  secretions 
even  when  food  was  taken  into  the  mouth.  These  emotions 
also  inhibited  the  movements  of  the  ahmentary  canal 
which  usually  serve  to  force  the  food  through  it.  Some 
of  the  effects  may  be  seen  in  man,  in  whom  vomiting  re- 
flexes are  caused  at  times  by  exceptionally  strong  emotions, 
particularly  by  sorrow  and  fear,  not  to  mention  the  sHghter 
reactions  always  present  in  disgust. 

The  Adrenal  Glands  in  Emotion. — Cannon's  experiments 
prove  definitely  the  importance  of  the  emotion  upon  the 
secretions  of  the  adrenal  glands,  small  glands  above  the 
kidneys.  It  has  been  shown  that  this  gland  is  called  into 
activity  by  stimulation  of  the  splanchnic  nerve,  a  nerve  of 
the  sympathetic  system.  The  gland  was  also  shown  to  be 
excited  in  most  of  the  violent  emotions,  by  pain,  anger,  fear, 
and  by  general  excitement.  The  effects  of  this  secretion 
are  widespread.  Briefly  enumerated,  it  serves  first  to  con- 
tract the  small  blood  vessels  and  to  increase  the  ease  with 
which  the  blood  will  clot.  This  action  may  be  illustrated 
by  the  use  made  of  it  by  the  physicians  in  applying  adrena- 
lin, the  substance  obtained  from  the  adrenal  glands  of  ani- 
mals, to  stop  superficial  bleeding.  A  second  action  of  the 
glands  is  to  increase  the  amount  of  glycogen,  or  so-called 
blood  sugar,  in  the  circulation.  This  seems  to  be  due  to  the 
action  of  the  adrenal  secretion  upon  the  liver,  causing  it  to 
release  its  stores  of  glycogen  and  pour  them  into  the  blood 
whence  they  are  carried  to  the  parts  of  the  body  that  may 
need  them.  A  secondary  consequence  of  these  actions  is 
that  the  effects  of  fatigue  are  checked  for  a  time,  and  the 


BODILY   RESPONSES    IN   EMOTION        489 

muscles  respond  with  renewed  strength.  This  is  due  in 
part  to  the  fact  that  the  constriction  of  the  blood  vessels 
increases  the  blood  pressure,  and  so  more  thoroughly  and 
quickly  washes  out  the  poisonous  products  of  earlier  action; 
and  in  part  to  the  fact  that  the  glycogen  furnishes  a  quickly 
assimilated  food  to  the  muscle.  It  could  be  demonstrated 
that  stimulation  of  the  adrenal  glands  produced  each  of 
these  effects,  the  blood  vessels  were  contracted,  the  blood 
pressure  increased  in  consequence,  the  composition  of  the 
blood  was  changed  so  that  it  coagulated  more  easily,  the 
liver  was  stimulated  to  secrete  its  sugar  and,  as  a  result, 
fatigued  muscles  were  temporarily  increased  in   strength. 

These  same  effects  were  all  produced  by  pain  or  strong 
emotion,  provided  the  adrenal  glands  were  present  and 
connected  with  the  sympathetic  system.  The  increase  of 
blood  pressure  in  emotion  is  well  known,  and  experiments 
showed  that  the  blood  would  coagulate  more  quickly  after 
strong  emotion.  The  increase  in  the  sugar  in  the  blood  was 
demonstrated  in  cats  subjected  to  pain,  or  which  had  been 
frightened  by  dogs  when  no  injury  could  be  done  them. 
The  same  effect  is  exerted  in  man.  It  was  found  that  of 
twenty-five  players  on  a  Harvard  football  squad  twelve 
had  increased  secretion  of  glycogen,  as  shown  by  sugar  in 
the  urine,  after  the  contest  was  over.  That  this  condition 
was  in  part  due  to  emotion  was  shown  by  the  fact  that  five 
of  the  twelve  were  substitutes  who  took  no  part  in  the  game 
and  that  the  only  excited  spectator  examined  also  showed 
the  same  reaction.  Students  examined  before  and  after  a 
difficult  and  important  examination  showed  presence  of 
glycogen  after,  but  not  before,  the  test. 

Looking  at  the  phenomenon  as  a  whole,  one  may  readily 
see  the  utility  of  these  reactions  in  emotions.  The  strong 
emotions,   particularly   the   unpleasant  emotions,    are   in 


490 


FUNDAMENTALS   OF  PSYCHOLOGY 


animals,  and  were  in  primitive  man,  very  likely  to  be  fol- 
lowed by  a  fight  or  other  violent  effort.  The  animal  subject 
to  emotion  must  usually  either  fight  or  run.  The  bodily 
changes  are  a  preparation  for  this  effort.  The  contraction 
of  the  blood  vessels  in  the  abdomen  forces  blood  into  the 
peripheral  vessels  and  the  respiratory  tracts,  preparing 
them  for  greater  effort  at  the  expense  of  the  digestive  tract, 
which  temporarily  ceases  its  function.  The  increased  glyco- 
gen and  more  rapid  circulation  under  excitement  supplies 
nourishment  to  the  muscles  and  removes  the  products  of 
fatigue,  thus  making  them  capable  of  greater  activity.  The 
constriction  of  the  arteries  and  quicker  clotting  of  the 
blood  serve  to  diminish  the  hemorrhage  in  case  wounds  are 
received  in  the  conflict.  All  together,  emotion  increases  the 
energy  of  the  individual  and  lessens  the  Habihty  to  injury. 
It  is  said  in  this  connection  that  an  artificially  induced  anger 
has  been  used  by  some  individuals  to  spur  them  to  greater 
effort. 

Identical  Reactions  for  All  Emotions.  —  Cannon  con- 
cludes from  his  experiments  that  all  the  activities  he  has 
studied  show  the  same  characteristics  for  all  vigorous  emo- 
tions, whether  pleasant  or  unpleasant,  whether  relatively 
passive  as  fear  or  active  as  anger.  All  this,  then,  must  be 
regarded  as  having  a  tendency  to  disprove  the  extreme  form 
of  the  motor  theory  of  emotion,  and  even^  to  narrow  the 
applicability  of  the  statement  that  the  characteristic 
qualities  of  emotion  are  dependent  exclusively  upon  the 
bodily  response.  This  theory  was  also  seriously  questioned 
by  Sherrington  as  a  result  of  experiments  upon  dogs  in 
whom  the  connection  between  body  and  head  had  been 
destroyed  by  sectioning  the  upper  part  of  the  cord.  After 
the  operation  they  showed  the  same  emotional  response  as 
before,  had  the  same  emotions  as  inferred  from  the  reactions 


BODILY   RESPONSES    IN   EMOTION        491 

of  the  muscles  of  the  head.  It  was  objected  that  associations 
may  have  been  formed  between  the  stimulus  to  the  emotion 
and  the  expression  of  the  muscles  of  the  head  by  the  inter- 
mediation of  the  bodily  responses,  and  that  these  connec- 
tions remained  after  the  sensations  from  bodily  responses 
had  been  cut  off.  This  objection  was  obviated  by  repeating 
the  experiments  on  puppies  only  three  weeks  old  who  had 
had  no  chance  to  form  this  indirect  association.  The  results 
in  this  case  were  the  same  as  before.  Sherrington  is  con- 
vinced that  the  emotion  is  the  result  of  cerebral  rather  than 
of  somatic  reactions. 

Is  Emotional  Quality  Due  to  Bodily  Response?  —  If  we 
accept  the  results  of  Cannon  and  Sherrington,  it  is  evi- 
dently necessary  to  ask  how  much  we  can  retain  of  the 
James  theory.  What  Cannon's  experiments  prove  is  that 
there  is  a  large  background  of  physiological  reaction  and 
probably  a  large  mass  of  sensations,  common  to  emotions 
of  all  types.  In  psychological  terms  one  can  say  that  all 
emotion  produces  an  excitement,  and  that  this  excitement 
has  a  common  quality  no  matter  what  the  occasion.  In 
this,  emotion  is  not  unlike  affection,  in  which  it  was  found 
necessary  to  give  up  the  old  statements  that  the  physio- 
logical responses  for  pleasure  and  pain  were  opposed.  We 
know  that  both  excite  the  same  changes  in  circulation,  secre- 
tion of  tears,  and  of  saliva.  To  this  now  we  may  add  that 
they  cause  the  same  secretions  of  adrenalin  and  the  same 
diminution  of  the  reflexes  of  the  alimentary  canal,  and  that 
emotions  differently  aroused  are  also  not  to  be  distinguished 
in  their  fundamental  physiological  effects.  The  possibility 
remains  that  on  top  of  these  common  elements  there  may 
be  other  responses  sufficiently  distinctive  to  constitute  the 
peculiar  qualities  of  the  different  emotions.  An  answer  to 
this  question  requires  more  detailed  investigation  than  has 


492        FUNDAMENTALS  OF  PSYCHOLOGY 

been  given  it,  for  in  spite  of  the  long  controversy  over  the 
James  theory,  relatively  few  accurate  and  extended  obser- 
vations have  been  recorded  of  the  sensations  that  come 
with  the  emotions. 

The  Distinguishing  Responses  of  the  Emotions.  —  If 
we  may  attempt  to  supply  the  lack  of  accurate  study  by 
making  use  of  chance  observation,  statements  of  noveUsts, 
psychologists,  and  acquaintances,  it  seems  that  facial  ex- 
pression, the  bodily  posture,  and  a  few  very  general  feel- 
ings offer  the  most  striking  means  of  differentiation.  There 
are  characteristic  differences  between  the  facial  expression 
in  grief  and  in  joy.  In  the  one  the  lines  of  the  face  are 
mostly  concave  downwards,  in  the  other  concave  upwards. 
The  bodily  posture  is  also  different,  drooping  and  con- 
tracted in  grief,  erect  and  expansive  in  joy.  Of  the  more 
internal  processes  the  most  evident  seem  to  be  an  elation 
in  joy  and  a  depression  with  grief.  One  gives  a  lightness 
that  seems  to  be  localized  in  the  chest,  the  other  a 
heaviness  with  its  seat  in  chest  or  abdomen.  No  one  of 
these  subjective  processes  has  been  referred  to  a  definite 
bodily  organ.  Strains  from  the  head  may  be  added,  but, 
after  all,  the  list  of  bodily  feelings  that  can  be  clearly 
distinguished  is  extremely  short.  Of  the  specific  emotions 
fear  may  be  distinguished  from  anger  by  the  general  weak- 
ness and  relaxation  of  the  one  and  the  general  consciousness 
of  strength  and  the  accompanying  activity  of  the  other. 
Disgust  may  include  sensations  of  incipient  movements  of 
rejection  of  food  either  from  the  mouth  or  oesophagus. 
Wonder,  to  complete  Shand's  fist  of  primary  emotions,  in- 
volves relatively  slight  sensations  of  strain  from  the  wide 
open  eyes  or  slightly  open  mouth,  together  with  the  quies- 
cence that  comes  from  the  cessation  of  movement.  That 
these  are  part  only  of  the  movements  or  sensations  involved 


BODILY    RESPONSES    IN    EMOTION        493 

in  any  of  the  emotions  considered  is  at  once  apparent. 
That  the  facial  expression  and  bodily  posture  are  not  suffi- 
cient in  themselves  to  account  for  the  awareness  of  emotion 
is  evident  from  James'  evidence  that  an  actor  might  act  a 
part  and  not  feel  the  emotion.  Careful  investigation  may 
be  able  to  go  much  farther  in  discovering  the  movements 
essential  to  each  emotion.  For  the  present  we  may  content 
ourselves  with  the  statement  that  on  a  background  of 
common  responses  which  furnished  the  excitement  —  an 
element  in  each  emotion  —  other  reactions  occur  which 
possibly  are  characteristic  of  each  emotion. 

The  Origin  of  Emotional  Responses.  —  For  the  simpler 
emotions  the  nature  of  their  responses  can  be  explained  at 
once  as  due  to  the  original  instinct.  As  McDougall  and 
others  before  him  put  it,  the  emotion  is  merely  the  conscious 
side  of  the  instinct.  When  one  runs  away  the  observer  sees 
the  running  with  its  accompanying  pallor  and  calls  it  the 
instinct  of  flight,  while  the  runner  has  the  emotion  of  fear. 
McDougall  parallels  each  of  his  instincts  with  an  emotion. 
Disgust  accompanies  repulsion;  wonder,  curiosity;  anger, 
pugnacity;  elation,  self-assertion,  in  the  same  way  that  fear 
accompanies  flight.  Watson  has  suggested  more  recently 
that  emotion  is  the  innately  determined  response  of  the 
autonomic  nervous  system,  while  instinct  is  the  innately 
determined  response  of  the  central  nervous  system.  One 
would  involve  the  reaction  of  glands  and  unstriped  muscles, 
the  other  of  skeletal  or  striped  muscles.  The  difference 
between  the  two  is  largely  as  to  whether  emotions  involve 
other  than  the  unstriped  muscles.  In  the  main,  emotions  are 
marked  by  the  internal  autonomic  responses.  There  are 
exceptions,  however,  which  destroy  the  complete  adequacy 
of  the  definition. 

On  either  theory  the  explanation  of  instinct  in  and  of 


494        FUNDAMENTALS   OF   PSYCHOLOGY 

itself  is  an  explanation  of  emotion.  This  holds  of  the  larger, 
more  useful  responses,  but  many  of  the  subtler  movements 
are  now  merely  expressive.  Even  these  can  be  explained 
directly  as  the  remnants  of  responses  once  useful  to  the 
preservation  of  the  organism  which  in  many  cases  have 
ceased  to  be  useful.  They  arose  as  did  all  instinct  by 
virtue  of  the  survival  of  the  organisms  that  developed  the 
responses,  or  by  the  dying  out  of  organisms  that  failed  to 
develop  them.  A  large  number  of  the  movements  can  be 
shown  to  be  direct  survivals  of  such  instinctive  responses. 
Running  away,  drawing  back,  or  the  start  of  fear,  evidently 
removes  the  individual  from  the  neighborhood  of  the  dan- 
gerous object.  Less  obvious  is  the  utility  of  the  trembhng 
and  loss  of  strength  that  come  momentarily  in  fear.  This 
may  be  traced  to  a  reduced  form  of  '  playing  possum'  or  of 
crouching  and  remaining  motionless  as  seen  in  the  rabbit 
and  other  defenceless  animals.  It  forces  them  to  remain 
motionless  and  thus  enables  them  to  escape  the  attention 
of  pursuers  and  possible  enemies.  The  cry  of  the  child  is 
similarly  useful  in  attracting  attention  when  it  is  alone  or  is 
uncomfortable.  In  each  of  these  cases,  the  conscious  state, 
the  emotion  proper,  is  probably  of  slight  value  but  seems  to 
be  an  unavoidable  accompaniment. 

General  Aspects  of  Emotion 

Theory  of  Transfer  of  Emotional  Expression.  —  Darwin 
has  suggested  that  three  other  classes  of  emotional  expres- 
sion must  be  recognized  which  serve  still  farther  to  explain 
or  at  least  to  classify  the  development  of  emotional  re- 
sponses. These  are  first,  that  when  an  emotion  or  a  condi- 
tion has  given  rise  to  one  form  of  expression,  a  similar  emo- 
tion or  situation  will  give  rise  to  a  similar  response.  The 
second  is  that,  granted  an  original  response,  an  opposed 


GENERAL  ASPECTS   OF   EMOTION         495 

situation  will  give  rise  to  the  opposite  response.  His  third 
class  is  that  in  which  certain  emotions  result  from  the  direct 
overflow  of  nervous  excitation  without  any  controlling  con- 
ditions. The  first  of  these  laws  is  illustrated  by  the  sneer, 
which  Darwin  refers  to  the  snarl  of  the  dog.  The  dog  when 
a  possible  enemy  approaches  exposes  the  teeth  and  prepares 
for  an  attack.  In  man  the  situation  is  similar  and  probably 
the  mental  attitude  also.  In  consequence  man,  too,  draws 
back  the  corners  of  the  mouth,  although  there  is  now  no 
thought  of  biting.  Similarly,  in  anger,  the  nostrils  are 
frequently  sHghtly  expanded,  although  there  is  now  no 
particular  utility  in  the  movement.  This  Darwin  would 
explain  as  preparation  in  the  animal  for  admitting  air  while 
the  mouth  was  stopped  with  the  hairy  body  of  the  antago- 
nist. The  expression  continues  although  the  original  occa- 
sion no  longer  exists.  The  second  class  is  more  open  to 
objection.  The  best  illustrations  are  furnished  by  the 
movements  of  a  cat  in  expressing  friendliness.  When  angry 
the  cat  crouches,  keeps  the  ears  back  where  they  will  not 
be  in  danger  of  injury;  the  tail  is  down  and  lashing  the  sides. 
When  pleased,  the  opposite  of  this  position  is  taken.  She 
is  erect  and  arches  the  back,  the  tail  is  held  high,  ears  erect. 
There  is  no  particular  reason  for  this  group  of  responses, 
and  Darwin  finds  it  in  the  law  of  antagonism.  The  mechan- 
ism that  leads  to  this  opposed  reaction  is  altogether  un- 
known, and,  as  we  have  seen  in  connection  with  the  feelings 
and  in  the  recent  studies  of  emotional  expression,  there  is 
no  evidence  of  a  tendency  to  opposition  in  the  expressions. 
The  third  class,  of  direct  overflow,  includes  all  that  cannot 
be  explained  under  the  other  heads.  Of  course  it  is  not 
really  a  new  head,  as  all  are  due  to  direct  overflow  of  nervous 
energy,  and  this  third  class  includes  only  such  forms  of 
expression  as  cannot  be  accounted  for  at  all.     Darwin's 


496  UNDAMENTALS   OF  PSYCHOLOGY 

instances  are  not  very  well  authenticated.  One  was  of  an 
individual  whose  hair  turned  gray  over  night  when  he  was 
condemned  to  die  in  the  morning;  the  report  being  based 
on  the  statement  from  hearsay  of  a  British  Indian  officer. 

Emotion  and  Language.  —  Certain  of  the  emotional  ac- 
companiments, in  fact  many  of  those  that  come  from  the 
more  external  and  voluntary  processes,  have  taken  on  a 
secondary  value  as  a  means  of  communication,  as  a  means 
of  indicating  to  another  the  state  of  one's  mind.  The  facial 
expressions  directly  convey  an  impression  of  the  emotion 
and  serve  as  warning  or  encouragement  to  the  companions 
to  cease  or  to  continue  the  line  of  action  that  they  happen 
to  be  pursuing  at  the  moment.  It  is  probable  that  the 
beginnings  of  articulate  speech  are  to  be  found  in  emotional 
expression.  Many  of  the  lower  animals  express  emotions 
through  sounds,  and  it  seems  possible,  even  probable,  that 
speech  came  from  the  association,  of  some  general  attitude 
of  the  individual  making  the  sound,  with  the  sound;  and 
that  little  by  Httle  other  associations  came  to  be  made  with 
it  until  our  present  fully  developed  languages  made  their 
appearance.  We  can  still  determine  the  emotional  tone 
from  the  modulations  of  the  voice.  The  loud  tones  and 
marked  accents  of  anger,  the  dragging  monotony  of  the 
whine  of  discontent,  the  softly  modulated  tones  of  affection 
show  the  emotional  state  very  much  mor'6  clearly  than  can 
any  exphcit  statement  in  words.  They  can  be  detected 
easily  in  speech  even  in  a  language  that  we  do  not  at  all 
understand,  and  convey  almost  as  much  of  the  emotional 
attitude  of  the  speaker  in  an  unknown  language  as  do  words 
in  our  own  tongue.  It  is  not  impossible  that  these  varying 
cadences  were  the  primary  forms  of  expression  and  commu- 
nication and  that  the  words  as  they  developed  have  been 
fitted  into  them. 


GENERAL   ASPECTS   OF    EMOTION         497 

Emotional  Reaction  to  New  Situations.  —  In  the  emo- 
tions of  our  second  class,  due  to  thwarting  or  furthering  of 
acquired  purposes,  the  explanation  of  why  the  movements 
should  be  aroused  is  not  so  direct.  As  was  said,  the  bodily 
reaction,  if  one  judge  from  immediate  consciousness,  is  the 
same  as  in  the  other  group.  Instead,  however,  of  having 
as  the  occasion  for  the  reaction  some  stimulus  that  has  an 
inherited  connection  with  it,  it  is  aroused  by  an  idea  or 
event  that  must  have  become  associated  with  it  through 
experience.  Thus,  anger  or  sorrow  over  the  loss  of  a  social 
honor  cannot  be  said  to  have  a  definitely  instinctive  origin, 
but  the  bodily  reaction  may  be  little  different  from  that 
excited  by  loss  of  a  dinner  and  may  continue  for  a  much 
longer  time  and  with  greater  intensity.  Part  of  this  transfer 
of  emotional  response  from  immediately  instinctive  to 
more  recently  developed  processes  may  be  explained  on  the 
analogy  of  Darwin's  laws.  A  vague  similarity  between  the 
more  complex  and  the  simpler  situation  leads  to  the  arousal 
of  the  same  instinctive  responses  for  both.  The  social  honor 
is  a  prize  which  through  the  effect  of  life  in  the  community 
has  become  as  desirable  as  a  bit  of  food.  When  it  is  lost,  the 
reaction  is  the  same  as  that  which  follows  the  loss  of  some- 
thing whose  appeal  is  instinctive.  Whatever  the  mechan- 
ism, certain  it  is  that  the  interrelations  of  acquired  tenden- 
cies and  their  interaction  with  the  environment  do  lead  to 
responses  identical  with  the  purely  instinctive. 

One  may  add  to  these  the  assumption  of  Dewey  that 
much  of  the  quality  of  emotions  may  be  due  to  conflict  or 
cooperation  between  the  habitual  responses.  These 
acquired  responses  might  stand  to  the  instinctive  responses 
as  the  acquired  ideals  and  needs  to  the  innate  or  instinctive. 
Possibly  the  interaction  of  systems  of  experience  or  of 
neurones  might  give  rise  immediately  to  a  conscious  quality. 


498        FUNDAMENTALS   OF  PSYCHOLOGY 

If  one  were  to  take  the  result  of  Sherrington's  experiments 
at  full  value  it  would  be  necessary  to  assume  some  such 
effects  and  qualities  of  purely  central  interactions.  Two 
loopholes  in  his  argument  make  this  conclusion  doubtful. 
His  experiments  left  his  pups  with  a  connection  between 
the  cortex  and  the  facial  muscles,  so  that  the  latter  might 
give  rise  to  the  emotional  content.  Secondly,  his  only 
evidence  of  emotion  was  the  facial  expression.  Really  all 
that  his  experiments  prove  is  that  one  may  have  the  facial 
expression  of  an  emotion  without  any  connection  between 
the  cortex  and  the  trunk  or  hmbs.  While  much  work 
remains  to  be  done  toward  relating  particular  emotions  to 
bodily  responses,  there  is  every  reason  to  beUeve  that  the 
quahty  of  the  emotion,  whether  it  be  immediately  instinc- 
tive in  origin  or  arise  from  interrelations  of  purposes  and 
acquired  ends,  is  due  in  large  part  to  reflex  activities.  Most 
of  the  response  is  common  to  all  sorts  of  emotion,  but  added 
qualities  probably  give  much  of  the  distinctive  tone  to  the 
separate  emotions. 

The  Kinds  of  Emotion.  —  While  the  quality  of  emotion 
may  be  accepted  as  in  large  part  determined  by  the  bodily 
resonance,  the  names  are  not  given  to  emotions  on  the 
basis  of  these  quahties.  This  may  be  due  in  part  to  the 
large  mass  of  sensations  common  to  all  emotions  and  in 
part  to  the  fact  that  emotions  are  usually  liamed,  if  named 
at  all,  after  they  have  ceased  to  act,  or  by  an  observer.  Dur- 
ing the  emotion  one  is  too  much  interested  in  other  things 
to  consider  its  quahties.  In  consequence  names  are  usu- 
ally given  on  the  criteria  of  the  causes  of  the  emotion  or  of 
its  outcome.  Perhaps,  too,  the  fact  that  fear  and  anger, 
love  and  jealousy,  and  other  emotions  are  so  nearly  indis- 
tinguishable is  to  be  found  partly  in  the  fact  that  one 
changes  into  another  with  great  rapidity.     Anger  is  dis- 


GENERAL   ASPECTS   OF   EMOTION         499 

tinct  from  fear  only  in  the  consciousness  of  power  or  weak- 
ness toward  the  intruding  man  or  object,  and  this  changes 
from  moment  to  moment  as  the  situation  is  faced.  One 
first  fears,  then  becomes  angry,  and  again  is  afraid,  as  long 
as  one  is  living  through  the  experience.  When  the  situa- 
tion is  properly  classified,  when  it  is  settled  that  one  is 
stronger  and  must  fight,  or  is  weaker  and  must  run,  the 
emotion  is  said  to  take  on  a  new  phase,  perhaps  even  to 
disappear.  If  one  assume  a  changing  response  or  perhaps 
a  conflict  of  responses  during  the  emotional  state,  it  is  no 
wonder  that  the  physical  accompaniments  of  opposed  emo- 
tions should  be  identical.  Both  physically  and  mentally 
the  two  fuse,  and  one  may  not  be  sure,  even  after  the 
event,  whether  fear  or  anger  was  dominant.  This  rapid 
alternation  of  expressions,  taken  together  with  the  fact 
that  there  are  always  identical  responses  in  the  sympa- 
thetic or  autonomic  system,  makes  classification  difficult 
in  practice,  and  then  largely  in  terms  of  the  intellectual 
antecedents,  the  nature  of  the  object,  and  the  outcome  of 
the  adventure.  It  is  this  that  led  the  popular  mind  and 
earlier  philosophers  to  the  classification  of  emotions  in 
other  than  motor  terms. 

Relation  of  Emotion  to  Other  Mental  Processes.  —  Emo- 
tions have  many  and  close  relations  with  the  other  mental 
processes.  In  many  cases  we  can  trace  the  development 
of  emotions  to  the  association  of  ideas.  The  occasion  for 
the  emotion  is  not  infrequently  to  be  found  in  a  recalled 
event.  The  reaction  in  this  case  is  usually  not  so  strong 
as  that  made  to  the  original  event  or  sensation,  but  has 
many  of  its  characteristic  qualities.  Often  it  seems  that 
there  is  an  association  between  emotional  states  them- 
selves. After  some  pleasant  emotion  the  liability  to  pain- 
ful response  is  decreased,  while  after  a  disagreeable  one,  all 


500        FUNDAMENTALS   OF  PSYCHOLOGY 

may  tend  to  produce  a  disagreeable  emotion.  After  one 
success  has  produced  elation  every  event  assumes  a  rose- 
ate hue,  —  one  is  easily  pleased,  the  emotion  of  joy  comes 
of  itself.  After  failure,  doubt  assails  with  each  new  ven- 
ture. Similarly,  after  one  fright,  fear  is  easily  aroused.  In 
short,  any  intense  emotion  leaves  a  predisposition  to  the 
same  or  similar  emotions. 

Emotion  has  so  many  similarities  to  feeling  that  it  is 
difhcult  to  draw  the  line  between  them.  Almost  all  emo- 
tions are  affectively  toned.  The  sole  exception  is  to  be 
found  in  surprise.  The  differences  between  feeling  and 
emotion  are  largely  in  degree.  The  affective  tone  is 
usually  stronger  in  emotion.  As  the  name  implies, 
the  motor  responses  are  more  striking  and  more  fully 
developed.  It  is  generally  true,  too,  that  the  cause  or 
occasion  for  the  emotion  is  to  be  found  on  the  perceptual 
•level,  in  a  stimulus  as  appreciated,  rather  than  in  the 
bare  sensation.  No  one  of  these  distinctions  can  be 
applied  without  exception,  but  all  taken  together,  now 
one,  now  another  predominating,  serve  to  draw  a  distinc- 
tion in  practice. 

In  their  relations  to  voluntary  acts  emotions  have  op- 
posed effects,  dependent  probably  upon  whether  we  con- 
sider one  or  the  other  type  of  emotions.  In  those  which 
have  an  ideational  occasion  and  are  to  be  regarded  as  in- 
terferences with  the  acquired  ends  of  the  individual,  the 
effect  of  emotion  is  generally  to  increase  the  motor  effi- 
ciency, at  least  in  the  coarser  acts.  The  more  primitive 
emotion,  the  subjective  accompaniment  of  an  intense  in- 
stinctive response  to  an  external  stimulus,  is  more  likely 
to  inhibit  voluntary  movements,  particularly  the  more  re- 
fined and  accurate  movements,  although  even  here  the 
actual  strength  is  increased  and  the  individual  is  probably 


GENERAL  ASPECTS   OF   EMOTION         501 

more  efficient  in  a  fight  or  in  flight.  Numerous  exceptions 
may  be  found  to  both  rules  and  exceptions.  Fear  or  even 
anger  may  leave  one  practically  helpless,  with  a  tremor  or 
weakness  that  prevents  all  movement  for  a  time  and  then 
probably  increases  the  capacity.  Again,  slight  emotion 
may  enable  one  to  carry  through  relatively  delicate  activ- 
ities, those  of  an  artistic  character,  for  example,  that  one 
might  not  be  capable  of  in  a  calm  moment. 

Emotional  Control.  —  One  may  control  emotions  in  some 
degree.  The  only  real  control  is  that  effected  at  the 
source.  The  nature  and  degree  of  an  emotion  depend  very 
largely  upon  the  way  a  situation  is  classified.  An  event 
frequently  may  be  referred  to  more  than  one  head  and 
will  arouse  a  different  emotion  under  each  of  these  classi- 
fications. A  human  brain,  presented  to  a  class  with  nu- 
merous references  to  what  the  individual  must  have  thought 
with  it,  and  with  other  remarks  that  emphasize  the  per- 
sonal side,  is  very  likely  to  arouse  intense  emotions;  but, 
if  considered  only  in  connection  with  tracts  and  structure, 
may  excite  mere  scientific  interest.  Many  of  the  events  of 
everyday  life  show  the  same  phenomenon.  Classify  a  re- 
mark or  the  man  who  makes  a  remark  in  one  way  and  you 
become  angry;  regard  it  or  him  in  another  light  and  you 
are  only  mildly  amused.  Much  also  may  be  done  by  pre- 
venting expression,  although  this  too  can  be  controlled 
only  by  changing  the  attitude  or  in  directing  attention  to 
something  else  until  the  occasion  for  the  emotion  is  past. 
Either  method  of  control  becomes  much  more  effective 
after  practice.  Like  everything  else,  attitude  and  response 
become  habitual;  instinctive  reactions  are  changed  by 
habit.  The  physician  or  surgeon  can  look  upon  patients 
as  cases  and  neglect  the  more  personal  relations.  Such 
professional  attitudes  are  taken  by  members  of  nearly  all 


502        FUNDAMENTALS   OF  PSYCHOLOGY 

professions   with   the  corresponding  development  or  sup- 
pression of  emotion  and  emotional  expression. 

Possible  Injuries  from  Control.  —  The  control  of  emo- 
tion has  taken  on  new  importance  with  recent  advances  in 
the  study  of  the  causes  of  nervous  and  mental  disease. 
Many  of  these  are  closely  related  to  the  emotions.  Ac- 
cording to  the  Freudian  school,  all  but  the  diseases  directly 
connected  with  diseased  tissues  are  to  be  explained  as  the 
result  of  conflicts  between  opposing  emotions  or  from  the 
checking  of  emotional  expression  by  social  pressure.  Re- 
pressing an  emotion  has  as  its  consequence  the  dissocia- 
tion of  that  experience  from  the  general  consciousness,  and 
the  repression  of  the  experience  into  the  unconscious  which 
may  result  in  hysteria,  with  its  train  of  paralyses,  anaesthe- 
sias, and  other  defects,  or  even  in  the  insanities  of  the  de- 
mentia precox  group.  The  extreme  advocates  of  the  the- 
ory argue  that  instincts  and  the  emotions  that  result  from 
them  should  be  given  free  rein,  that  any  interference 
might  result  in  a  disease  or  in  increasing  the  KabiUty  to 
disease.  Taken  in  the  broadest  sense  this  would  be  sub- 
versive of  all  discipline  and  would  probably  be  worse  for 
society  than  the  presence  of  a  few  hysterics  or  even  insane. 
On  the  other  hand  constant  and  unnecessary  repression  of 
all  instincts,  such  as  is  seen  in  famiKes  dominated  by  a  too 
solicitous  mother  or  overbearing  father,  ckn  be  avoided 
without  any  serious  social  consequences,  and  may  save 
the  mental  health  of  the  child.  The  motto  should  be 
free  vent  for  instincts  wherever  there  is  not  too  much 
injury  to  others,  with  discipline  restricted  to  essentials 
and  exercised  with  as  much  consideration  as  possible. 
Where  repression  is  necessary  it  should  be  made  to  take, 
as  far  as  possible,  the  form  of  a  transformation  to  some 
other    object    than    that    usually   given    it.     Control    by 


MENTAL  STATES  RELATED  TO  EMOTION     503 

changing  the  classification  of  the  stimulus  is  also  relatively 
harmless. 

Conclusions  Concerning  Emotion.  —  We  may  think  of 
emotion,  then,  as  a  disturbance  of  the  usual  or  normal 
course  of  any  succession  of  thoughts  or  activities  by  the 
intrusion  of  a  new  or  extraneous  event.  This  event  re- 
sults in  a  more  or  less  prolonged  disturbance  of  the  activ- 
ities, accompanied  by  many  useless  and  incoordinated  re- 
sponses, and  by  intense  affection.  It  is  possible  to  distin- 
guish two  types  of  emotion,  or  at  least  two  extremes  of 
emotion.  One,  usually  the  more  violent  but  usually  of 
short  duration,  is  directly  dependent  upon  instinct,  both 
in  condition  and  response.  This  is  the  type  that  may  be 
defined  as  the  mental  accompaniment  of  an  instinct.  The 
second  type,  which  is  usually  of  shghter  intensity  and 
greater  duration,  is  conditioned  by  the  thwarting  or  fur- 
thering of  the  system  of  purposes  developed  by  the  indi- 
vidual upon  an  instinctive  basis.  Even  for  this  class  the 
responses  are  also  of  instinctive  origin.  In  this  latter  case, 
however,  we  must  look  to  the  mental  antecedents  rather 
than  to  the  physical  responses  as  the  cause  of  the  emotion, 
and  as  the  determinant  of  the  type  of  emotion  that  shall 
be  induced  by  the  stimulus.  The  bodily  reverberation  de- 
pends upon  the  antecedent  mental  states  rather  than  being 
itself  a  first  cause  and  constituting,  through  the  sensations 
it  excites,  the  entire  emotion.  This  is  not  to  deny  impor- 
tance to  the  movements  in  giving  color  to  emotion;  it 
merely  insists  that  other  factors  must  be  considered  in  dis- 
cussing its  origin. 

Other  Mental  States  Related  to  Emotion 

Sentiment.  —  Sentiment  is  ordinarily  used  to  designate 
the  milder,  more  lasting  forms  of  emotion.     Shand  has 


504        FUNDAMENTALS   OF  PSYCHOLOGY 

varied  the  application  of  the  term  to  indicate  the  antece- 
dent condition  of  emotions,  the  system  of  impulses  that 
dominates  the  individual,  which,  when  furthered  or  hin- 
dered, gives  rise  to  the  emotion.  The  sentiments  are  for 
him  dependent  upon  the  instincts,  but  the  instincts  are  in 
turn  modified  and  developed  by  experience.  The  two 
great  systems  are  love  and  hate.  These  are  fundamental, 
constitute  the  impelling  forces  of  all  activity,  and  give  rise 
to  emotion  when  acted  upon  by  particular  events.  When 
aroused  they  are  or  may  be  directed  toward  particular  per- 
sons or  objects.  They  approach  the  particular  emotion 
rather  than  the  fundamental  tendencies  which  constitute 
the  impelling  force  needed  for  the  development  of  emo- 
tion. This  definition  emphasizes  the  characteristic  of  du- 
ration implied  in  the  usual  meaning  of  the  word,  and  has 
been  accepted  by  McDougall  and  Stout.  There  is  no 
doubt  that  a  name  is  needed  which  shall  designate  the 
systems  of  impulses  or  purposes.  However,  some  word 
implying  greater  force  would  be  better  than  sentiment, 
since  these  systems  are  the  forces  behind  all  voluntary  ac- 
tivities, mental  and  physical,  as  well  as  the  occasions  for 
the  emotions.  What  is  designated  is  more  like  what  is  usu- 
ally called  desire  or  a  system  of  desires  than  sentiment. 
While  the  authority  behind  this  definition  of  the  word  en- 
titles it  to  respect,  sentiment  seems  better^suited  to  desig- 
nate the  mild  continued  emotion,  its  more  usual  meaning. 

Mood  and  Passion.  —  Mood  is  a  predisposition  to  an 
emotion  of  comparatively  short  duration.  It  may  be  due 
to  physical  causes.  Lack  of  sleep,  a  fit  of  indigestion,  and 
many  other  indispositions  predispose  to  unpleasant  emo- 
tions, while  good  health  and  rest  conduce  to  pleasant  emo- 
tions or  sentiments.  Moods,  too,  develop  from  earlier 
emotions.     A  disagreeable  emotion,   as  was  said  above, 


MENTAL  STATES  RELATED  TO  EMOTION     505 

leaves  a  tendency  to  other  unpleasant  emotions,  and  this 
is  a  mood.  Moods,  then,  are  rather  dispositions  to  emo- 
tions than  any  particular  kind  of  consciousness  or  behavior 
of  themselves.  Passion,  like  sentiment,  has  been  used  in 
various  ways  at  different  times  and  by  different  men,  now 
being  extended  to  cover  the  entire  field  of  pleasant  and  un- 
pleasant acts  or  mental  states,  and  again  restricted  to  the 
more  \dolent  exhibitions  of  the  emotional  reaction.  At 
present  it  can  hardly  be  said  to  have  any  technical  mean- 
ing. As  in  the  popular  sense,  it  most  frequently  designates 
the  more  violent  forms  of  emotion. 

Temperament.  —  Temperament  is  a  word  with  a  long 
pedigree  in  psychological  usage  and  one  that  has  under- 
gone little  change  in  application  since  first  introduced. 
Galen  recognized  four  humors  in  the  body,  blood,  phlegm, 
black  bile,  and  yellow  bile,  and  assumed  that  the  disposi- 
tion of  the  individual  was  largely  determined  by  the  one 
that  was  dominant.  These  gave  rise  respectively  to  four 
principal  temperaments,  the  sanguine,  the  phlegmatic,  the 
melanchoUc,  and  the  choleric.  These  names  still  persist, 
although  they  have  taken  on  slightly  different  forms  at  the 
hands  of  different  psychologists  and  in  the  popular  mind. 
Thus  Wundt  makes  the  temperaments  depend  upon  com- 
binations of  rate  and  strength  of  response  in  a  given  indi- 
vidual. The  sanguine  is  said  to  be  quick  and  weak,  the 
choleric,  quick  and  strong,  the  melanchoUc,  slow  and  strong, 
the  phlegmatic,  slow  and  weak.  This  corresponds  to  cer- 
tain of  the  characteristics  of  the  terms  as  popularly  used, 
but  omits  what  seems  the  most  important,  the  tendency  to 
pleasant  or  to  unpleasant  emotions.  On  the  whole,  the 
schematism  of  Wundt  has  little  to  recommend  it  over  the 
looser  applications  of  the  term  in  popular  speech.  All  to- 
gether it  can  hardly  be  said  that  we  know  more  about  tern- 


So6        FUNDAMENTALS   OF  PSYCHOLOGY 

peraments  than  that  individuals  differ  in  their  susceptibility 
to  the  different  emotions.  At  present  there  is  no  com- 
plete classification  of  these  dispositions.  The  ideal  of  Ga- 
len, that  one  might  group  individuals  in  such  a  way  that  it 
would  be  possible  to  determine  what  mental  and  physical 
capacities  and  dispositions  were  necessarily  associated  and 
find  some  simple  test  that  would  determine  to  which  of 
these  classes  each  individual  belonged,  is  almost  as  remote 
to-day  as  it  was  when  Galen  wrote. 

The  Ductless  Glands  in  Relation  to  Mood  and  Tem- 
perament. —  A  very  suggestive  recent  theory  would  relate 
temperament  and  mood  to  the  dominant  action  of  various 
glands  of  internal  secretion,  the  endocrine  or  ductless 
glands.  We  have  seen  that  the  adrenal  glands  are  sup- 
posed to  be  an  effective  factor  in  the  excitation  of  the  emo- 
tions. The  other  ductless  glands  may  by  their  secretions 
prepare  the  way  for  emotional  outbursts  or  for  the  re- 
straint of  the  emotions.  Those  most  frequently  men- 
tioned are  the  thyroids,  the  pituitary,  and  on  less  definite 
evidence  the  thymus.  It  is  assured,  for  example,  that  ex- 
cess of  thyroid  secretion,  as  in  Graves'  disease,  renders  the 
subject  much  more  excitable  and  more  responsive  to  both 
pleasant  and  unpleasant  emotions.  Lack  of  the  normal 
amount  of  secretion  decreases  intelligence.  The  posterior 
part  of  the  pituitary  body,  a  gland  on  the  anterior  side  of 
the  mid-brain,  secretes  a  fluid  into  the  blood  which  has  a 
tendency  to  increase  contraction  of  the  involuntary  mus- 
cles. Less  well  based  is  the  suggestion  that  the  thymus  if 
active  for  too  long  in  the  life  of  the  individual  induces  the 
persistence  of  a  childish  disposition.  The  various  secre- 
tions act  through  the  blood  either  on  the  nervous  or  mus- 
cular tissue  to  produce  these  effects.  This  modern  theory 
would  replace  Galen's  humors  by  the  names  of  these  duct- 


MENTAL  STATES  RELATED  TO  EMOTION     507 

less  glands.  If  accepted  we  would  have  the  thyroid  tem- 
perament, the  pituitary  temperament,  the  thymus  tem- 
perament, etc.  It  is  undoubtedly  an  advance  on  Galen, 
and  promises  much  for  the  future. 

REFERENCES 

James:  Principles  of  Psychology,  Vol.  II,  Ch.  XXV. 

Shand:  Foundations  of  Character. 

Darwin:  Expression  of  Emotions  in  Animal  and  Man. 

Ribot:  Psychology  of  Emotions. 

Jastrow:  Temperament  and  Character. 

Watson:  Psychology  from  the  Standpoint   of  a    Behaviorist, 

Ch.  VII. 
Herman:  The  Glands  Regulating  Personality. 


CHAPTER  XVII 

THE   GENERAL  PRINCIPLES  OF  ACTION 
AND   THE  WILL 

Action 

The  final  outcome  of  all  thought,  of  all  mentai  processes 
whatsoever,  is  action.  In  connection  with  the  nervous 
system  it  was  seen  that  all  stimulations  tend  to  find  an 
outlet  through  the  motor  nerves  and  muscles.  Movements 
play  an  important  part  in  almost  all  mental  states.  Move- 
ments  accompany  all  acts  of  attending,  and  several  authori- 
ties explain  the  fact  of  attention  itself  by  the  movements 
called  out,  rather  than  by  the  antecedent  mental  states. 
In  perception,  movements  are  used  as  a  means  of  explain- 
ing space,  time,  and  rhythm;  recognition  is,  for  some 
authorities,  merely  a  revival  of  old  movements.  We  find 
many  writers  who  explain  many  if  not  all  of  the  essentials 
of  the  reasoning  processes  in  terms  of  movement.  Either 
as  beginning,  intermediate  stage,  or  end,  of  every  mental 
state,  we  find  that  action  has  an  important  place  in  fact 
or  theory. 

We  may  assume  in  our  present  chapter  that  action  is 
the  real  aim  of  Hfe,  and  that  most  of  the  operations  so  far 
discussed  are  prehminary  to  it.  This  action  may  follow 
immediately  upon  them,  or  may  be  delayed  for  a  consider- 
able period.  Here,  however,  we  are  more  concerned  to 
see  how  the  other  processes  lead  to  action,  than  to  under- 
stand how  the  movements  may  explain  them.  In  the  first 
place,  we  may  assert  with  some  confidence,  on  the  basis 
508 


ACTION  509 

of  practically  universal  agreement  of  psychologists  of  to- 
day, that  there  are  no  new  forces,  nor  even  any  absolutely 
new  laws  involved  in  the  control  of  action.  All  mental 
states -give  rise  to  movements  of  greater  or  less  extent; 
and,  on  the  other  hand,  movement  as  a  psychological  process 
can  be  explained  only  in  terms  of  certain  mental  states 
already  discussed.  Were  we  to  give  a  complete  explanation 
of  movement,  we  should  have  a  review  of  each  of  the  pre- 
ceding chapters,  with  an  appendix  on  the  way  in  which 
movement  resulted  from  the  process  discussed  in  it.  We 
can  at  most  add  the  appendix  matter  in  this  chapter. 
Assuming  that  the  fundamental  principle  of  action  is  that 
all  excitations  tend  to  pass  over  from  the  sensory  to  the 
motor  neurones,  we  may  raise  several  fundamental  questions 
in  connection  with  this  process  which  may  be  discussed 
or  put  aside  now  before  we  proceed  to  the  details. 

Sensation  and  Movement.  —  One  of  the  most  important 
is  whether  the  sensory  excitation  that  leads  to  movement 
must  be  accompanied  by  sensation.  The  evident  answer 
is  that  sensation  may  or  may  not  accompany  the  process. 
Some  assert  that  normally  all  movement  comes  from 
sensation,  but  we  have  also  the  opposite  view  that  all 
sensation  is  aroused  by  the  excitation  of  the  motor  neurone 
or  even  by  the  movement  itself.  Neither  of  these  extreme 
views  need  concern  us  here.  We  may  be  content  with  the 
statement  that  the  excitation  of  motor  processes  certainly 
often  takes  place  with  no  accompanying  sensation,  and 
that  all  that  is  really  necessary  for  the  movement  is 
the  previous  excitation  of  some  sensory  organ  or  sensory 
neurone.  This  latter  .may  come  through  some  indirect 
path  involving  a  memory,  or  the  cortical  cells  ordinarily 
active  in  memory.  The  natural  thing  is  for  the  sensory 
process  to  discharge  into  movement.     What  really  needs 


5IO        FUNDAMENTALS   OF   PSYCHOLOGY 

explanation  is  why  at  times  the  sensory  excitations  do  not 
cause  movements.  In  the  complete  sense  they  probably 
never  fail  to  arouse  some  response,  but  it  is  frequently  too 
slight  to  be  noticed.  The  fundamental  fact  of  action  in 
general  needs  no  special  explanation. 

Learning 

The  Methods  of  Learning.  —  Starting  with  the  single 
assumption  that  movements  always  follow  upon,  and  are 


Fig.  94.  —  Animal  problem  box.     (From  Thorndike,  "Animal  Intelligence.") 


the  outcome  of  sensory  stimulations,  the  first  question 
that  confronts  us  is  the  discovery  of  what  it  is  that  de- 
termines the  particular  movement  which  shall  follow  upon 
any  given  stimulation.  We  have  seen  that  certain  con- 
nections are  present  in  the  organism  at  birth,  the  result  of 
the  heredity  and  evolution  of  the  individual  and  of  the 
species,  and  that  learning  by  trial  and  error  controlled  by 


\ 


LEARNING  511 

instinct   supplies   the   remainder.     We  may  here  give   a 
more  detailed  account  of  the  process  of  learning. 

The  experiments  upon  animals  were  begun  by  Thorndike, 
who  tested  the  methods  by  which  a  cat  learned  to  escape 
from  a  bo.x  that  had  a  door  fastened  by  a  simple  catch,  a 
button  that  could  be  turned,  or  a  bolt  that  might  be  drawn 
by  pulling  a  string  hanging  down  inside  the  box.  To 
make  sure  that  the  cat  would  make  an  effort,  it  was  hungry 
when  put  into  the  box,  and  food  was  in  sight  on  the  outside. 
The  process  of  learning  has  been  found  to  depend  in 
practically  all  animals  upon  the  presence  of  random 
movements,  —  is  one  of  trial  and  error.  The  cat 
makes  a  large  number  of  movements  of  all  sorts,  tries 
to  force  herself  through  all  promising  openings,  bites 
at  all  projections,  scratches,  and  mews;  in  fact,  she 
exhausts  all  the  acts,  reflex,  instinctive,  and  habitual, 
that  she  has  at  her  command.  Sooner  or 
later   one  presents   itself    that  happens   to 

open  the 
door.      She 

~  I         I  I  I  scratches  at 

the   button 

Fig.  95.  —  Curve  of  learning  in  dogs.     Height  shows  time  required 

for  hitting  upon  each  correct  response.     (From  Thorndike.)         and  bypure 

chance 
turns  it.  When  the  door  is  open  she  walks  out.  But  one 
successful  movement  does  not  teach  her  the  method  of 
opening  the  door.  When  put  in  again,  she  goes  through  a 
series  of  random  movements  a  second  time,  and  again  will 
hit  upon  the  correct  response  by  chance.  It  is  only  after 
a  number  of  successes  —  the  number  varies  with  the  in- 
telligence of  the  animal  —  that  the  right  movement  will 
be  begun  at  once  when  the  animal  is  put  into  the  box. 
Each  trial  will,  on  the  average,  require  less  time  than  the 


512        FUNDAMENTALS   OF   PSYCHOLOGY 

one  that  preceded  it,  but  there  are  many  variations  owing 
to  chance  difficulties. 

This  process  of  learning  by  trial  and  error  governs  all 
of  the  learning  of  animals  so  far  experimented  upon  from 
the  very  lowest  to  man.  How  low  in  the  scale  we  may  go 
depends  upon  what  is  meant  by  learning.  In  the  early 
chapters  it  was  noted  that  Jennings  found  that  movements 
were  modified  by  the  results  of  earlier  actions  even  in  the 
unicellular  organisms.  The  Stentor,  for  example,  would, 
when  slightly  stimulated,  at  first  bend  to  one  side  and  then 
later  give  up  all  responses.  If  the  stimuli  were  made 
more  intense,  it  would  first  bend  away  sharply,  and  then, 
after  several  responses  which  failed  to  remove  it  from  the 
excitation,  would  release  its  hold  and  swim  away.  This, 
the  most  rudimentary  form  of  learning,  is  nevertheless 
learning.  From  that  point  on,  more  and  more  complex 
movements  may  be  acquired  as  the  organism  increases 
in  complexity.  The  essentials  of  the  learning  process  in 
animals  seem  to  be  that  any  problem  must  be  solved 
by  chance  at  first;  that,  after  the  right  movements  have 
been  hit  upon  a  sufficient  number  of  times,  a  connection 
is  estabhshed  between  a  certain  stimulus  or  group  of  stimuli 
and  the  movement,  in  such  a  way  that  the  stimulus  tends 
at  once  to  call  out  the  corresponding  movement. 

The  Nervous  Basis  of  Learning.  —  This  still  leaves  open 
the  question  as  to  what  brought  the  so-called  chance  re- 
sponse in  the  first  place.  If  we  turn  back  to  the  nervous 
system,  it  may  be  said  that  a  given  sensory  impression 
stimulates  a  sensory  neurone,  which  in  its  turn  has  axones 
connected  with  a  number  of  motor  neurones.  The  synapse 
to  one  of  the  motor  neurones  probably  offers  least  resistance 
and  the  impulse  passes  across  that.  If  the  result  which 
comes  from  the  act  gives  pain  or  does  not  remove  the 


LEARNING  513 

unpleasant  stimulus,  a  new  set  of  responses  will  be  started 
as  the  stimulus  becomes  strong  enough  to  open  less  per- 
meable synapses.  If,  for  example,  the  cat  does  not  escape, 
get  the  meat,  and  in  consequence  begin  the  instinctive 
responses  involved  in  eating,  then  new  synapses  will  be 
opened  and  other  movements  result  until  some  change 
in  the  stimulation  starts  a  new  series  of  responses.  It 
should  be  remembered  that  there  is  not  one  stimulus  but 
many,  and  that,  as  attention  changes,  new  stimuH  come 
which  also  make  possible  new  movements.  When  the 
movement  has  been  made,  the  same  stimulus  will  produce 
the  same  movement,  and  each  repetition  reduces  the  re- 
sistance at  the  synapse  as  in  the  formation  of  association. 
In  animals  and  in  the  ordinary  learning  of  man,  each  move- 
ment is  the  result  of  instinctive  responses  or  of  earlier 
habits.  Watson  asserts  that  there  is  no  real  formation  of 
new  connections  in  learning,  but  that  all  is  due  to  the 
elimination  of  certain  of  the  unnecessary  movements  in 
the  first  trials.  His  theory  is  that  the  inherited  connec- 
tions usually  offer  roundabout  paths  between  stimulus  and 
movement.  This  series  of  responses  is  innate.  Trial  and 
error  finally  make  a  more  direct  connection  between  the 
stimulus  and  the  successful  act.  On  this  theory  learning 
could  never  lead  to  absolutely  new  connections.  It  could 
only  shorten  the  course.  Undoubtedly  a  large  part  of 
learning  is  of  this  character. 

To  What  Extent  are  New  Connections  Formed  in  Learn- 
ing? —  In  man,  however,  there  seem  to  be  cases  in  which 
there  is  no  natural  nervous  connection  at  the  synapses, 
or  at  least  in  which  the  instinctive  connection  is  very  weak, 
and  in  which  learning  takes  place  through  a  spread  of 
impulses  over  synapses  very  sUghtly  permeable.  Thus, 
in  learning  to  move  the  ears  in  the  experiments  that  Bair 


514        FUNDAMENTALS   OF  PSYCHOLOGY 

carried  out,  a  connection  was  formed,  a  path  of  discharge 
was  opened  to  a  muscle  not  ordinarily  under  voluntary 
control.  Here  there  seemed  to  be  a  gradual  spread  of 
impulse  from  the  usual  channels  to  more  and  more  unusual 
ones,  until  finally  it  chanced  to  find  the  old  path  to  the 
retrahens  muscle,  the  muscle  that  pulls  the  ear  back. 
Then  repetition  stamped  in  the  connection  until  it  could 
be  repeated  at  will.  Another  case  of  the  formation  of  new 
connections  is  furnished  by  the  surgical  operation  that 
replaces  an  impaired  nerve  by  another  with  an  altogether 
different  central  connection.  Thus,  when  there  has  been 
paralysis  of  the  nerve  innervating  the  flexor  muscle  of  the 
arm,  it  has  been  possible  to  divide  the  nerve  supplying 
the  extensor  muscle  and  connect  one  part  of  it  with  the 
injured  flexor  muscle.  When  it  has  regenerated,  the  nerves 
that  previously  produced  extension  of  the  arm  now  carry 
the  impulses  which  produce  flexion.  Here  evidently  we 
cannot  be  deahng  with  a  dropping  out  of  old  connections 
but  must  have  the  formation  of  altogether  new  ones.  Even 
more  convincing  are  the  experiments  and  treatments  of 
Lasher  and  Franz.  They  showed  that  a  monkey  which 
had  had  an  arm  paralyzed  by  extirpation  of  the  controlUng 
area  in  the  cortex  would  completely  recover  the  use  of  the 
arm  if  forced  to  use  it,  although  there  was  no  regeneration 
of  tissue.  Constant  trial  induced  similar  recovery  of  func- 
tion in  men  in  cases  of  long-standing  paralysis  due  to  disease. 
These  paralyses  must  be  overcome  by  the  opening  of  new 
connections  between  sensory  and  motor  neurones  by  the 
process  of  trial  and  error.  All  three  instances  involve 
formation  of  connections  that  are  not  definitely  present  at 
birth;  in  the  second  instance,  in  fact,  they  follow  paths 
and  produce  movements  the  reverse  of  those  that  are  in- 
nate.    Indeed,  much  evidence  is  accumulating  that  there 


LEARNING  515 

is  considerable  variation  in  the  paths  followed  during  the 
same  function  of  the  cortex.  If  confirmed,  this  fact  would 
prove  that  the  formation  of  new  connections  is  the  rule 
rather  than  the  exception. 

The  Acquisition  of  Skill.  —  In  the  adult  man  the  most 
important  practical  problem  of  learning  is  how  series  of 
acts,  already  under  control  in  isolation,  may  be  united 
into  a  single  series,  and  made  to  constitute  a  unitary  group. 
This  is  what  happens  when  one  acquires  skill  in  any  game 
or  occupation.  A  number  of  investigations  have  been 
carried  out  on  problems  of  this  sort.  Bryan  and  Harter  ^ 
investigated  the  learning  of  the  telegraphic  language; 
Swift  studied  typewriting,  tossing  balls,  and  learning 
Russian;  Bair  and  Book  investigated  typewriting.  All 
obtained  the  same  general  result,  that  skill  comes  rapidly 
at  first  and  then  more  slowly,  and  that  in  the  course  of  the 
work  there  are  many  periods  in  which  no  progress  is  made, 
followed  by  periods  of  rapid  improvement.  In  each  of 
these  tasks  the  individual  movements  are  known  in  advance. 
One  can  press  the  key  of  a  telegraph  instrument  or  of  the 
typewriter  or  toss  a  ball  at  the  start.  What  is  necessary 
is  to  organize  the  whole  so  that  one  element  shall  start  the 
next,  and  all  shall  be  carried  on  together  without  false 
movements,  and  as  rapidly  as  is  possible.  All  agree  that 
improvement  here,  Hke  the  original  learning,  comes  largely 
by  chance  successes.  One  hits  upon  some  more  effective 
combination  of  movements  without  any  definite  foresight, 
and  even  without  knowing  what  it  was  that  caused  the 
improvement.     The  worker  does  his  best  all  along,  and  at 

<■  Bryan  and  Harter,  Studies  on  the  Telegraphic  Language,  Psychological 
Review,  1897,  p.  27. 

Swift,  Acquisition  of  Skill  in  Typewriting,  Psychological  Bulletin, 
Vol.  I,  p.  295. 


Si6        FUNDAMENTALS   OF  PSYCHOLOGY 

times  an  improvement  comes,  at  times  it  does  not.     There 
is  always  fluctuation  from  day  to  day.     This  seems  due  in 


1100 
1050 
1000 
950 
900 
850 
800 
750 
700 
650 
600 
550 
500 
450 
400 


^=-      T      4- 

i 

4                m^ 

4                -4 

4             -aI 

1           r 

t        \ih^ 

I w  V             --  " 

L   JaW. 

t-tt 

t-t 

A   ^ 

P- 

} 
_4 

7 

t 

0   5  10  15  20  25 


35  40  45  60 


Fig.  96.  — Curve  of  learning  to  write  on  the  typewriter.  The  horizontal  distances 
show  the  number  of  days  of  practice;  the  vertical,  the  number  of  words  written  in 
an  hour.  Curve  i  shows  the  progress  during  the  original  practice;  curve  2,  the  re- 
sults of  nine  days'  practice  after  an  interval  of  two  years  and  thirty-five  days. 
(From  Swift.) 

part  to  the  general  physical  condition,  in  part  to  chance 
changes  in  the  character  of  the  work.     The  preliminary 


LEARNING  517 

feeling  offers  little  or  no  indication  of  what  the  course  of  the 
work  is  to  be.  One  may  feel  well,  even  feel  certain  that  a 
good  score  is  to  be  made  on  a  certain  day,  and  find  that 
the  accompUshment  is  lower  than  on  days  when  the  general 
feeling  seems  to  offer  less  hope  of  success. 

Plateaus  in  Learning.  —  One  of  the  most  interesting 
questions  is  why  there  should  be  the  long  periods  of  no 
progress,  the  so-called  plateaus.  They  have  been  reported 
by  all  observers  and  are  present  in  most  of  the  curves. 
The  same  amount  of  effort  is  made,  and  all  the  conditions 
seem  to  be  approximately  the  same,  but  no  progress  results 
for  a  long  interval.  Various  explanations  are  given  for 
them.  Bryan  and  Harter  assert  that  they  are  periods  in 
which  the  old  associations  or  partial  habits  are  being  more 
firmly  implanted,  and  that  this  is  essential  for  any  farther 
advance.  In  certain  cases  this  seems  true.  It  has  also 
been  asserted  that  they  are  periods  in  which  the  worker 
loses  interest  and  relaxes  effort,  but  most  workers  do  not 
accept  this  as  a  general  explanation.  They  are  also  found 
when  effort  is  kept  at  a  maximum.  Assuming  that  the 
plateaus  are  necessary  as  preparation  for  a  new  advance, 
the  reason  for  the  rise  to  a  new  level  offers  difficulties. 
Three  explanations  have  been  suggested,  (i)  The  simplest 
is  that  the  preparation  has  been  completed  and  then  some 
new  combination  of  movements  is  hit  upon  that  makes 
the  progress  possible.  (2)  Even  Bryan,  who  argues  that  a 
plateau  is  a  period  of  preparation  for  increased  efficiency, 
insists  that  there  is  often  at  least  some  special  stimulus. 
He  quotes  instances  of  telegraphers  who  have  spent  some 
time  in  a  small  office  who  show  a  sudden  rise  in  ability  when 
transferred  to  a  main  line  office.  Here  increase  is  probably 
the  result  of  new  incentives.  (3)  A  third  important  factor 
Hes  in  becoming  clearly  aware  of  the  conditions  of  the  prob- 


5i8        FUNDAMENTALS   OF  PSYCHOLOGY 

lem,  of  what  must  be  done  to  gain  full  control,  —  with  this 
there  is  frequently  an  increase  of  skill.  Effort  may  be 
helpful,  or  may  not,  according  to  the  time  at  which  it  is 
exerted.  If  all  is  ready,  increased  effort  may  give  increased 
effectiveness;  if  the  effort  comes  too  soon,  it  may  be  a 
detriment  and  even  lead  to  postponement  of  the  advance. 
Batson^  carried  out  an  investigation  of  the  learning  pro- 
cess for  tossing  balls.  His  conclusion  is  that  the  plateaus 
are  the  expression  of  the  time  taken  to  associate  several 
movements  into  a  chain,  when  the  separate  movements 
must  be  combined  into  a  unit  before  new  progress  is  possi- 
ble. Thus,  keeping  two  balls  in  the  air  with  one  hand 
requires  three  separate  acts,  estimation  of  direction,  esti- 
mation of  the  right  height  to  throw  the  balls  or  of  the  force, 
and  estimation  of  the  time  required  for  the  balls  to  rise  and 
fall,  since  the  ball  is  seen  only  at  its  highest  point.  Unless 
these  three  acts  could  be  made  together,  no  real  progress 
was  possible.  The  plateaus  were  thought  to  correspond  to 
the  periods  during  which  the  three  factors  were  being  com- 
bined, or  during  which  each  was  being  learned  separately 
before  they  could  be  combined.  If  the  act  to  be  learned  was 
simple,  involving  only  one  process,  no  plateaus  were  found. 
If  attention  was  distributed  over  the  entire  process,  if  all 
three  part  processes  were  attended  to  at  all  times,  the 
plateaus  were  not  so  likely  to  appear.  In  Batson's  experi- 
ments they  were  found  only  in  composite  acts  where  the 
parts  were  attended  to  separately  and  then  joined  into 
groups.  Whether  this  explanation  will  hold  for  all  problems 
can  be  determined  only  when  others  have  been  analyzed 
into  their  parts  in  a  similar  way.  We  may  content  our- 
selves here  with  the  statement  that  acquiring  skill  in  com- 

1  Batson,  Acquisition  of  Skill.    Monograph  Supplement,  Psychological 
Review,  Vol.  XXI,  1916. 


LEARNING  519 

plex  acts  is,  like  learning  in  the  simpler  forms,  due  to 
chance  trial  and  error,  a  process  in  which  the  learner  does 
not  know  how  he  makes  advances  either  before  or  after  they 
are  made.  The  associations  are  formed  through  frequent 
repetition,  and  the  plateaus,  or  stages  of  no  progress,  are 
periods  when  associations  necessary  to  new  progress  are 
being  formed.  The  rise  comes  through  some  new  acciden- 
tal combination,  due  to  some  new  incentive,  to  an  under- 
standing of  the  conditions  of  the  advance,  or  merely  to  the 
perfection  of  preUminary  connections  essential  to  making 
new  combinations  possible. 

Learning  by  Imitation.  —  A  suggestion  that  may 
deserve  a  moment's  notice  is  that  one  may  learn  by  imita- 
tion. In  one  sense  this  is  of  course  very  largely  true.  We  ^ 
tend  to  imitate  the  more  striking  acts  of  those  in  whom  we 
are  interested  and  with  whom  we  come  into  contact.  But 
at  most  this  acts  as  a  goal  toward  which  one  may  strive  by 
a  process  of  trial  and  error,  rather  than  as  an  immediate 
cause  of  the  action.  That  there  is  no  fundamental  impulse 
to  imitate  is  evident  from  experiments  made  with  animalsV 
Thorndike  found  that  when  one  cat  was  permitted  to  watch 
another  get  out  of  a  cage  a  number  of  times,  the  time  it 
required  to  make  the  same  movements  was  not  noticeably 
shortened.  Similar  results  have  been  obtained  by  various 
other  investigators  under  approximately  the  same  condi- 
tions. In  his  work,  referred  to  above,  Bair  found  that  even 
compelHng  the  muscle  to  make  the  movement  to  be  learned 
by  stimulating  it  by  an  induction  current  did  not  decrease 
the  time  required.  The  impulse  must  develop  from  the 
cue  or  stimulus  ordinarily  used  to  incite  the  movement,  if 
learning  is  to  take  place.  External  aid  serves  at  most  to 
direct  attention  to  the  right  movement;  but  to  make  it, 
if  it  be  not  already  learned,  requires  the  usual  process  of 


520        FUNDAMENTALS   OF   PSYCHOLOGY 

trial  and  error.  The  same  statement  may  be  made  of  the 
effect  of  imitation  in  more  complex  acts  that  are  already  at 
command.  The  sight  of  another  making  them  serves  to 
give  the  idea,  and  that  may,  if  desired,  lead  to  the  act. 
What  force  it  has  is  due  to  the  general  social  instincts,  rather 
than  to  any  specific  instinct  or  impulse  to  imitate. 

Movement 

Consciousness  and  Movement.  —  When  one  attempts 
to  determine  the  factors  that  precede  and  control  move- 
ments already  learned,  to  ask  why  the  movement  is  made 
and  how  it  is  controlled,  one  comes  upon  rather  more 
difference  of  opinion.  We  have  already  seen  that  all  move- 
ment follows  upon  stimulation.  These  stimulations  can 
be  traced  in  the  last  analysis  to  sensory  excitation.  In 
most  of  the  more  elaborate  acts  of  human  adults,  some 
consciousness  accompanies  this  excitation,  and  in  a  very 
large  number  of  cases  the  excitation  that  precedes  is  from 
the  activity  of  a  memory  tract  rather  than  from  the  stimu- 
lation of  a  sense  organ  directly.  Each  of  these  factors 
introduces  certain  comphcations  and  raises  questions  that 
must  be  discussed.  One  of  the  first  is,  what  does  conscious- 
ness add  to  the  process  and  is  it  necessary  that  consciousness 
should  be  present?  Here  opinions  differ.  Consciousness 
does  accompany  many  if  not  most  acts  when  they  are  first 
made.  On  the  other  hand,  before  an  act  has  been  definitely 
learned,  consciousness  of  what  is  to  be  done  seems,  as  has 
been  said,  to  help  very  httle  in  the  learning;  after  it  has 
been  learned,  consciousness  becomes  more  and  more  indefi- 
nite until  finally  it  may  completely  disappear.  In  view 
of  these  facts  it  seems  difficult  to  do  more  than  insist  on 
the  importance  of  the  sensory  innervation  as  universally 
present.    The  degree  of  consciousness  and  what  its  effect 


MOVEMENT  521 

upon  movement  is,  may  be  left  an  open  question;  and  its 
presence  need  be  pointed  out  only  where  what  is  conscious 
gives  a  definite  explanation  of  the  characteristics  of  the  act. 
Initiation  of  a  Movement. —  We  may  divide  the  conscious 
accompaniments  of  movements  into  three  groups.  First, 
the  initiating  processes;  secondly,  the  directing  sensory 
processes;  third,  the  awareness  of  the  result.  These  must 
be  considered  separately.  What  the  initiating  process  may 
be  has  been  much  discussed,  and  many  suggestions  have 
been  made  concerning  it.  Probably  all  have  been  too 
definite.  Thus,  several  have  inchned  to  the  view  that 
movement  must  be  preceded  by  the  kina^sthetic  sensation 
that  arises  when  the  movement  is  made.  To  speak  a  word, 
one  must  recall  the  sensations  made  when  that  word  has 
been  uttered  at  some  earher  time;  or  to  move  the  hand  to 
cut  the  leaf  of  a  book  one  is  reading,  one  must  recall  the 
sensations  felt  when  that  movement  was  made.  Woodworth^ 
has  shown  that  these  sensations  are  seldom  present,  and  a 
little  observation  will  indicate  that  you  do  not  ordinarily 
have  them  in  mind  before  the  movement  is  made.  Visual 
images  are  more  frequently  present,  but  even  these  are  not 
always  definite.  If  you  decide  to  rise  and  walk  across  the 
room,  you  will  see  that  all  that  is  necessary  is  to  notice  a 
book  and  remember  that  you  must  read  something  in  it 
before  you  go  on.  With  a  very  general  idea  and  the  sight 
of  the  book,  the  movement  begins  and  is  carried  to  its  con- 
clusion. Even  visual  images  are  not  always  present.  This 
is  too  obvious  to  mention  in  the  case  of  speech,  which  is 
influenced  more  by  auditory  images.  In  most  cases  the 
imagery  that  precedes,  whose  presence  may  be  regarded 
as  constituting  the  intention  to  move,  is  very  schematic; 

1  Wood  worth:  The  Cause  of  a  Voluntary  Movement.     Garman  Volume, 
P-  3SI. 


522        FUNDAMENTALS   OF  PSYCHOLOGY 

and  almost  anything  in  any  way  related  to  the  act  may  serve 
as  the  incentive  to  movement. 

Meaning  as  an  Incentive.  —  In  this,  action  is  very  little 
different  from  thought.  In  fact,  Woodworth  first  came  to 
his  hypothesis  of  imageless  thought  through  a  study  of  the 
mental  content  that  precedes  action.  As  in  thinking,  our 
memories  and  ideas  are  brought  into  systematic  groups, 
in  which  any  one  element  may  serve  to  represent  any  other, 
so  the  antecedents  of  acts  are  also  grouped,  and  the  act 
results  from  the  appearance  of  any  element  of  the  system. 
Organization  is  as  evident  in  the  control  of  action  as  in  the 
control  of  thought.  Just  as  an  idea  which  is  not  at  all  simi- 
lar to  an  object  may  represent  that  object,  so  an  idea  or 
sensation  that  has  been  only  indirectly  associated  with  a 
movement  may  come  to  represent  that  movement  and  in 
fact  constitute  the  intention  to  make  it.  In  practice  one 
finds  that  almost  any  idea  or  impression  that  has  been 
connected  with  an  act  may  be  the  immediate  predecessor 
of  that  act.  Any  mental  process  may  constitute  the  incen- 
tive to  any  act  with  which  it  has  been  closely  associated, 
in  the  same  way  that  any  image  may  have  as  its  meaning 
any  idea  with  which  it  has  been  associated.  Colloquial 
language  connects  the  two,  and  uses  the  single  word  for 
both.  '  I  mean  to  do  that '  is  a  common  expression  as  the 
equivalent  of  'I  intend  to  do  that,'  and  the  use  of  the  term 
is  justified  by  psychological  analysis.  A  meaning,  using 
the  term  in  the  technical  sense  of  the  earlier  chapters,  may 
quite  as  naturally  have  an  issue  in  movement  as  stop  short 
in  the  mere  representation  of  an  idea. 

Different  Types  of  Antecedents  of  Movements.  —  Three 
distinct  classes  of  mental  processes  may  be  discovered 
among  the  antecedents  of  action,  (i)  The  most  common 
is  the  intention  or  the  meaning,  a  representation  in  some 


MOVEMENT  523 

form  of  the  goal  or  result  of  the  act.  This  goal  may  be 
represented  as  a  concrete  sensation,  as  a  very  general 
notion,  or  may  have  no  appreciable  imagery,  or  at  least  no 
appreciated  imagery.  It  may  take  any  of  the  forms  of  a 
concept.  The  initiating  idea  for  a  stroke  at  golf  may  be  a 
definite  image  of  the  point  where  the  ball  is  to  land,  it  may 
be  some  vague  verbal  thought  that  it  is  well  to  land  near 
the  tree  on  this  hole,  or  it  may  be  that  the  stroke  is  guided 
by  nothing  more  definite  than  the  assumption  that  the 
next  stroke  is  in  that  general  direction,  an  assumption  that 
is  not  formulated  but  is  due  to  the  appreciation  of  a  particu- 
lar step  in  the  game.  It  must  be  said  that  this  stage  is  very 
rare  in  a  game  of  skill,  but  much  more  frequent  in  partially 
automatized  tasks.  (2)  At  times,  intention  is  lacking  or 
much  in  the  background,  and  a  sensation  or  idea  closely 
associated  with  the  movement  serves  as  the  incentive. 
This  may  be  either  the  kina^sthetic  image  mentioned  above, 
or  it  may  be  the  sight  of  an  object,  as  when  a  spot  on  the 
tablecloth  catches  the  eye,  and  the  finger  moves  towards 
it  even  to  the  later  embarrassment  of  guest  and  hostess. 
The  second  cue  is  different  from  the  first  in  that  it  does  not 
correspond  to  a  purpose,  or  may  be  directly  opposed  to  the 
general  purpose.  (3)  Finally,  some  sensory  stimulus  may 
cause  a  movement  that  is  altogether  unrelated  to  the  inten- 
tion of  the  moment. 

Interaction  of  Incentives.  —  These  three  different  sorts  of 
antecedents  may  oppose  and  disturb  each  other  in  the  con- 
trol of  the  resulting  movement.  The  intention  is  the  most 
frequent  antecedent  but,  if  at  any  point  in  carrying  out 
the  intention  an  extraneous  idea  be  permitted  to  become 
dominant  in  consciousness,  it  disturbs  or  prevents  the  move- 
ment. Thus,  if  one  is  making  a  golf  stroke  and  suddenly 
permits  the  ditch  immediately  in  front  to  catch  attention, 


524        FUNDAMENTALS   OF   PSYCHOLOGY 

the  ball  goes  into  the  ditch  in  spite  of  the  good  general 
intentions  of  the  player.  In  a  baseball  game,  in  the  same 
way,  if  some  object  other  than  the  point  at  which  the  ball 
should  be  thrown  is  attended  to,  a  bad  play  is  fairly  certain 
to  result.  Even  the  attachment  of  a  not  to  an  idea  does 
not  always  prevent  it  from  affecting  the  act.  Langfeld  ^ 
found  that  in  experiments  which  consisted  in  moving  a 
wire  along  a  groove,  endeavoring  to  avoid  touching  the 
sides,  the  experimenters  were  more  likely  to  touch  the  edge 
if  he  asked  them  not  to  touch  it  than  if  he  told  them  to  keep 
the  wire  in  the  middle  of  the  groove.  Attention  to  the  side 
induced  a  movement  toward  it  in  spite  of  the  intention  to 
avoid  it.  Within  limits,  trying  not  to  do  a  thing  has  the 
same  effect  as  trying  to  do  it.  This  is  particularly  true  in 
acts  of  skill  and  of  movements  only  partly  learned.  It  is 
true  in  general  that  an  intention  of  the  more  remote  sort 
is  frequently  conquered  by  an  idea  of  a  specific  movement, 
even  if  that  be  directly  contrary  to  the  intention.  The  same 
holds  of  the  third  type  of  antecedent,  a  sensation  not 
directly  connected  with  the  movement.  A  sudden  stimulus 
that  comes  in  the  course  of  an  attempt  to  make  a  difficult 
movement  will  frequently  disturb  or  destroy  it.  A  sudden 
loud  noise  or  bright  light  spoils  a  delicate  Hne  with  the  pen, 
or  the  aim  of  a  rifle,  or  a  drive  at  golf.  Not  the  meaning 
alone,  but  that,  together  with  the  idea  or  object  that  holds 
attention,  or  the  sensory  stimulus  that  forces  its  way  into 
consciousness,  serves  to  direct  the  movement. 

The  Control  of  Movements.  —  The  sensations  aroused 
by  the  movement  constitute  the  second  of  the  three  groups 
of  conscious  states  accompanying  movement.  These  sen- 
sations serve  primarily  to  direct  the  act.     Movement  is 

1  Langfeld,  Movement  under  Positive  and  Negative  Suggestion.  Psy- 
chological Review,  Vol.  20,  p.  459. 


MOVEMENT  525 

in  this  respect  much  like  memory  or  reasoning  or  the  process 
of  learning.  The  incentive  must  be  distinguished  from  the 
control;  the  attempt,  from  the  recognition  of  success  or 
failure,  together  with  the  correction  that  goes  with  the 
latter.  In  addition  to  the  sensory  processes  that  initiate 
the  movement,  the  accompanying  sensations  exercise  a 
constant  guidance.  These  are  divided  by  James  into  two 
classes,  the  resident  and  remote  sensations.  The  resident 
are  the  kinaesthetic  sensations.  The  remote  are  the  sensa- 
tions from  eye  or  ear,  that  indicate  where  the  moving  mem- 
ber is,  or  what  the  sound  is  that  is  being  produced.  Both 
of  these  sensations  or  groups  of  sensations  ordinarily  control 
the  movement  without  being  directly  noticed.  As  a  finger 
is  moved  with  the  eyes  closed,  the  kinaesthetic  sensations 
are  constantly  coming  to  the  cortex  and  sending  out  reflexes 
which  serve  properly  to  direct  the  movement  and  to  adjust 
its  force  and  extent.  They  are  most  easily  demonstrated 
by  their  absence.  In  tabes  the  motor  nerves  are  unimpaired, 
but  the  posterior  columns  in  the  cord  which  carry  the  kines- 
thetic sensations  are  destroyed.  A  characteristic  symptom 
of  the  disease  is  inability  to  control  movements.  When  the 
eyes  are  closed,  the  patient  is  not  able  to  bring  thumb  and 
finger  together  accurately  and  still  less  to  bring  two  fingers 
together  in  front  of  the  face  with  a  single  sweep.  Locomotor 
ataxia  with  its  irregular  gait  is  one  form  of  the  disease. 

Remote  Sensations.  —  The  remote  sensations  are  also 
active  in  detecting  and  correcting  any  departures  from  the 
intended  course  of  action.  Thus,  when  writing,  if  the  hand 
starts  to  make  a  crooked  fine,  the  deviation  is  at  once  seen, 
and  the  eye  directs  the  pen  back  to  the  right  path.  The 
influence  of  the  eye  is  not  appreciated ;  but,  if  one  attempts 
to  write  with  the  eyes  closed,  it  is  at  once  apparent  that  an 
important  correcting  force  is  lacking.    The  ear  acts  in  the 


526        FUNDAMENTALS   OF  PSYCHOLOGY 

same  way  in  governing  speech  and  the  tone  in  singing.  Ex- 
periments show  that  most  singers,  some  of  them  among  the 
most  famous,  are  not  able  to  strike  the  correct  tone  at  once, 
but  make  an  attempt,  are  quick  to  detect  that  the  tone  is 
too  high  or  too  low,  and  so  adjust  the  pitch  to  the  correct 
one.  The  violinist,  too,  does  not  estimate  the  position  of 
his  fingers  on  the  string  by  the  kin  aesthetic  sensations,  an 
estimation  that  would  require  marvellous  accuracy,  but 
approximates  the  position  first,  and  then,  as  the  bow  begins 
to  give  the  tone,  he  adjusts  the  length  of  the  string  until 
his  ear  tells  him  that  the  tone  is  correct.  That  the  remote 
sensation  is  essential  is  shown  by  the  fact  that  the  deaf 
cannot  speak  without  special  training.  The  training  con- 
sists in  teaching  the  patient  to  control  the  voice  by  kinaes- 
thetic  and  tactual  sensations  instead  of  by  the  sounds  that 
are  used  by  the  individual  who  hears.  The  deaf  child 
feels  the  teacher's  vocal  organs,  and  keeps  trying  until  he 
makes  his  own  carry  out  the  same  movements.  The  same- 
ness of  movement  is  at  first  recognized  by  touch,  but  with 
practice  the  kinaesthetic  sensations  from  the  vocal  organs 
suffice.  These  control  processes  also  become  automatic,  so 
that  one  notices  neither  the  sensations  themselves  nor  the 
fact  that  they  exercise  control.  The  sensations  from  the 
eye  guide  the  hand  reflexively,  or  with  as  Httle  thought  as 
is  required  for  the  reflex. 

Another  striking  case  of  reflex  guidance  of  this  sort  is 
that  exerted  by  the  static  sense,  the  stimuh  from  the 
vestibular  branch  of  the  auditory  nerve.  This,  as  was  seen 
in  the  earher  chapters,  makes  close  connections  with  the 
motor  centres  in  the  brain  stem,  particularly  with  the 
cerebellum  and  the  roots  of  the  motor  ocuU  nerves.  These 
sensory  nerves  probably  give  no  sensations,  but  nevertheless 
they  guide  the  movements  of  the  body  as  a  whole,  serve  to 


MOVEMENT  527 

keep  the  balance,  give  rise  to  compensatory  eye  movements, 
—  movements  that  keep  the  eyes  fixed  on  the  same  point 
in  spite  of  the  movements  of  the  head  and  body.  The 
sensory  impulse  calls  out  these  movements  continuously 
and  often  we  have  no  knowledge  that  the  movement  has 
been  made;  certainly  we  have  no  appreciation  of  the  fact 
that  they  produce  the  movements.  The  stream  of  im- 
pulses coming  in  through  the  vestibular  nerves  constitutes 
one  of  the  important  forces  which  control  any  movement 
of  the  trunk. 

Any  act,  then,  may  be  said  to  be  the  outcome  of  the  appre- 
ciation of  a  situation  that  requires  movement.  The  imme- 
diate incentive  is  usually  some  object  or  idea  that  for  the 
moment  holds  the  centre  of  attention.  But  this  incentive 
is  seldom  the  picture  of  the  movement  to  be  made;  more 
frequently  it  is  some  idea  of  the  end  to  be  accompUshed. 
If  the  movement  is  relatively  unfamiliar,  it  is  an  idea  of  some 
immediate  act;  if  very  familiar,  a  more  remote  end  is  usu- 
ally held  in  mind.  The  intention  does  no  more  than  mean 
the  movement;  it  seldom  recalls  it  in  sensory  terms.  The 
movement  is  always  guided  by  the  resident  and  remote 
sensations.  These  adjust  it  to  the  conditions  of  the  moment. 
When  a  movement  has  been  repeated  sufficiently  often  to 
become  automatic,  attention  is  needed  only  at  the  be- 
ginning. The  act  is  started,  and  attention  then  turns  to 
something  else;  the  association  between  the  movements  and 
the  resident  and  remote  sensations  serves  to  carry  it  to  its 
goal.  Thus,  in  walking  on  a  familiar  course,  one  merely 
decides  to  go  to  a  certain  place  and,  when  once  started,  one 
step  starts  the  next,  always  under  the  control  of  the  remote 
and  resident  sensations.  The  visual  stimuh  lead  to  the 
avoidance  of  obstacles  and  guide  in  making  the  necessary 
turns.    Unless  some  new  obstacle  is  encountered,  one  may 


528        FUNDAMENTALS   OF  PSYCHOLOGY 

go  into  a  '  brown  study '  at  the  moment  of  starting  and  not 
realize  again  what  is  going  on  about  until  the  destination 
has  been  reached.  All  movements  or  chains  of  movements, 
at  first  learned  or  joined  together  by  effort  and  under  the 
influence  of  a  complete  consciousness,  tend  gradually  to 
lose  more  and  more  of  the  conscious  accompaniments  and 
antecedents.  Finally,  in  more  complex  acts,  they  may  start 
from  some  unnoticed  stimulus;  in  the  case  of  simple  acts 
or  a  number  of  unified  simple  movements,  they  may  be 
started  by  a  single  idea,  may  be  initiated  by  a  conscious 
process  and  guided  to  their  end  by  habit  without  further 
consciousness.  Associations  between  the  movements  them- 
selves or  between  the  resident  sensations  of  one  movement 
and  the  motor  processes  required  for  the  next,  take  the 
place  of  all  more  definite  awareness.  Even  in  these  auto- 
matic acts,  there  is  guidance  by  a  wide  group  of  habitual 
connections  between  neurones,  not  at  all  appreciated  by 
the  agent. 

Choice 

Choice  and  Motives.  —  We  have  been  assuming,  all 
through,  that  the  intention  to  make  a  movement  has  been 
present,  but  a  process  antecedent  to  the  intention  requires 
discussion.  This  is  the  problem  of  choice.  It  is  true  that 
most  acts  are  automatic  or  habitual,  that  the  decision  was 
determined  long  before  the  time  of  pesforming  the  act, 
and,  when  the  occasion  presents  itself,  is  carried  out  im- 
mediately. But  in  some  instances  two  opposed  acts  are 
felt  to  be  possible,  and  it  is  necessary  to  choose  which  is  to 
be  made.  The  actual  act  of  choice  is  relatively  simple.  It 
amounts  merely  to  giving  one  intention  free  play  and 
checking  the  others.  The  actual  mental  content  consists 
in  attending  to  the  movement  to  be  made  or  the  result  to 
be  attained.    When  the  choice  or  decision  is  made  long  be- 


CHOICE  529 

fore  it  is  to  be  carried  into  effect,  it  consists  frequently  in 
outlining  the  course  of  action  in  words  or  in  some  idea,  — 
some  concept  perhaps.  When  the  time  comes,  the  stimuli 
present  lead  at  once  to  the  act.  The  only  new  problem 
in  connection  with  choice  is  as  to  what  leads  to  the  inten- 
tion, why  one  course  is  chosen  rather  than  another.  This 
depends  upon  the  selection  of  one  or  the  other  of  the  possible 
ends  present  to  consciousness.  The  explanation  Hes  finally 
in  the  laws  of  attention  and  association,  and  offers  little 
that  is  new.  The  deciding  factors  are  the  subjective  con- 
ditions of  attention  and  of  association.  One  seldom  re- 
gards as  choice  the  decision  determined  by  objective  fac- 
tors alone. 

Mental  Attitude  in  Control  of  Choice.  —  The  influence 
of  the  situation  and  the  mental  setting  or  context  have 
been  frequently  mentioned  above.  It  was  brought  out  in 
a  slightly  different  form  by  Ach^  in  a  long  investigation 
of  the  conditions  of  choice  by  means  of  the  reaction  experi- 
ment. First  he  asked  his  subjects  to  move  the  right  finger 
when  a  letter  E  was  shown,  and  the  left  when  the  letter  O 
came.  The  times  required  for  making  each  movement  were 
measured.  It  was  found  that  no  real  decision  was  made 
after  the  cards  were  shown,  but  that  the  movements  were 
made  at  once  because  of  the  previous  preparation.  This  is 
evident  from  the  fact  that  more  time  was  required  when 
the  subject  was  left  free  to  react  with  either  finger  than 
when  the  finger  to  be  moved  was  prescribed.  In  the  latter 
case  part  of  the  preparation  for  action  had  been  completed 
before  the  movement  began.  These  facts  may  be  regarded 
as  indicating  that  the  first  form  of  reaction  gives  play  to 
choice,  while  the  others  are  determined  by  the  conditions 
of  the  experiment,  the  purpose  of  the  moment.  It  was  in 
1  Ach,  Ueber  die  Willenstatigkeit  und  das  Denken. 


530        FUNDAMENTALS   OF  PSYCHOLOGY 

these  same  experiments  that  the  control  of  the  arithmetical 
associations  was  studied.  When  two  numbers  were  shown 
one  above  the  other  and  the  observer  was  told  in  advance 
to  add  or  subtract,  the  result  came  at  once  or  after  a  rela- 
tively short  time.  When,  on  the  other  hand,  the  numbers 
were  shown  with  no  instructions,  the  resulting  process  was 
much  delayed,  and  the  observer  had  a  chance  to  study  the 
process  of  choice.  The  task  or  purpose  serves  to  control 
choice  just  as  it  does  to  determine  association.  The  effect 
of  the  purpose  is  replaced  by  the  situation  and  the  general 
intentions  of  the  moment  in  many  choices  of  everyday  life. 
It  is  this  that  leads  one  to  take  an  umbrella  when  the  sky 
is  cloudy,  and  a  cane  when  it  is  clear,  as  one  goes  past  the 
rack  in  the  hall;  to  choose  a  serious  volume  when  one 
comes  into  the  study  in  working  hours,  and  a  novel  or  the 
newspaper  in  the  period  just  after  dinner.  In  all  these 
things,  the  choice,  while  apparently  undetermined,  is  guided 
by  the  general  attitude  and  the  environment. 

More  Remote  Influences  in  Choice.  —  In  more  compU- 
cated  and  important  instances  of  choice,  the  final  selection 
is  similarly  determined,  but  the  controlUng  influences  are 
much  more  numerous.  The  final  release  comes  with  think- 
ing of  the  end  to  be  accomplished  with  the  full  behef  that 
the  act  is  to  be  carried  out.  The  antecedent  processes  are 
much  Hke  the  balancing  of  decisions  in  (Joubt  before  full 
behef  presents  itself.  First  one  alternative  is  thought  of, 
then  another.  After  these  alternations  have  repeated 
themselves  several  times,  one  finally  dominates,  is  held  in 
mind,  and  the  others  are  by  that  very  fact  excluded;  the 
decision  is  made.  The  forces  that  favor  the  possible  alter- 
natives are  to  be  found  in  the  instincts  on  the  one  side  and 
the  social  forces  on  the  other.  They  constitute  what  are 
called  the  motives.    The  motives  are  themselves  ordinarily 


THE   WILL 


531 


quite  largely  out  of  consciousness.  One  knows  only  that 
one  course  of  action  or  another  is  preferable  but  has  no 
knowledge  why  it  is  preferred.  Carrying  this  back,  we  see 
that  of  the  possible  lines  of  conduct  the  one  is  chosen  which 
proves  most  attractive.  Why  it  is  attractive  is  determined 
by  natural  endowment  and  education.  There  is  no  trace 
of  what  is  commonly  called  will. 

The  Will 

Is  there  a  Peculiar  Will  Element?  —  A  problem  much 
discussed  since  the  beginning  of  psychological  theory  is 
whether  there  is  a  specific  quality  or  a  specific  function, 
apart  from  those  outlined  above,  which  can  be  called  the 
will.  The  earlier  writers,  always  tending  to  discover  a 
separate  faculty  or  force  for  each  of  the  words  in  common 
use,  hardly  questioned  the  existence  of  something  of  the 
kind,  something  which  was  an  actual  force  in  decisions  and 
an  incentive  to  action.  As  the  direct  examination  of  men- 
tal states  began  to  take  the  place  of  speculation  with  only 
inaccurate  observation,  fewer  and  fewer  men  were  able  to 
discover  this  peculiar  state.  Instead,  an  ever-increasing 
number  of  authorities  found  the  final  cause  of  action  in  an 
idea  that  was  attended  to,  in  an  idea  of  movement  with 
the  belief  that  it  was  to  take  place,  or  in  the  feeling  qual- 
ities preceding  or  accompanying  the  idea.  As  more  and 
more  work  was  done  upon  the  analysis  of  the  consciousness 
preceding  action,  the  less  was  there  found  that  was  pecu- 
Har  to  this  state. 

Recent  investigators,  Ach  and  Michotte  and  his  follow- 
ers, have  revived  the  old  doctrine  in  a  slightly  new  form. 
In  certain  of  his  more  complicated  reaction  time  experi- 
ments, Ach  asserts  that  it  is  not  merely  holding  the  idea 
of  the  movement  in  the  centre  of  consciousness  that  evokes 


532        FUNDAMENTALS  OF  PSYCHOLOGY 

the  movement,  but  that  in  addition  to  this  it  is  necessary 
that  the  self  become  momentarily  identified  with  the  move- 
ment to  be  made.  At  the  moment  the  self  is  thus  identi- 
fied with  the  one  alternative,  the  choice  is  made,  and  the 
action  is  determined.  A  somewhat  similar  statement  is 
made  by  Michotte  in  connection  with  a  choice  between 
operations  upon  numbers  as  a  result  of  experiments  carried 
on  by  himself  and  Priim.^  In  a  second  experiment,  also  on 
reaction  times,  conducted  with  Barrett,-  measurements 
were  made  of  the  time  required  to  choose  between  two 
Hquids  and  to  drink  one  of  them.  The  liquids  represented 
different  degrees  of  pleasantness  and  unpleasantness.  They 
were  tested  in  advance  and  designated  by  letters  that 
should  have  no  associations  other  than  those  which  devel- 
oped during  the  experiment.  The  observer  was  to  watch 
carefully  what  preceded  the  decision  and  to  determine  if 
possible  what  was  the  deciding  factor  in  his  choice.  In 
this  series  of  experiments  the  element  of  voluntary  choice 
seemed  less  important.  In  fact,  Barrett  regarded  the  re- 
sult as  proof  that  choice  is  made  and  executed  without 
any  pecuhar  new  activity  that  could  be  designated  an  act 
of  volition.  Instead,  he  found  that  one  arranged  the  tastes 
as  they  were  learned  in  order  of  agreeableness;  and,  when 
they  were  presented,  the  value  on  this  scale  was  an  imme- 
diate guide  to  the  choice.  The  whole  choice  was  com- 
pleted when  the  hquid  had  been  given  its  letter  and  place 
in  the  series.  He  finds  that  the  determinants  of  the  act 
are  approximately  the  same  as  those  we  have  enumerated 
above.     Michotte  ^  in  reply  reasserts  his  behef  in  a  pure 

1  Michotte  and  Priim,  Etude  experimentale  sur  le  choix  volontaire  et  ses 
antecedentes  immediates,  Archives  de  psychologie,  Vol.  X,  p.  113. 

-  Barrett,  Motivation  Tracts  and  Motivation  Forces. 

^  Michotte,  A  propos  de  contributions  recentes  a  la  psychologie  de  la 
volonte,  Ann.  de  L'Institute  Super,  de  Phil.,  No.  ix. 


THE  WILL  533 

act  of  volition  which  must  intervene  in  all  acts  of  choice, 
whether  related  to  action  or  not,  and  after  the  choice  is 
made  must  again  intervene  in  the  execution  of  the  act  in- 
volved in  the  choice.  He  beheves  that  the  selection  of  one 
from  a  group  of  liquids  of  known  value  tends  to  render  the 
process  more  automatic,  and  that  this  accounts  for  the 
smaller  part  played  by  voluntary  choice. 

This  difference  of  opinion  between  Barrett  and  Michotte 
is  typical  of  the  opposing  possibihties  in  the  explanation 
of  a  voluntary  act.  On  the  one  hand,  emphasis  is  placed 
upon  the  more  remote  underlying  conditions;  on  the  other, 
upon  the  necessity  for  discriminating  between  the  alterna- 
tives by  holding  in  mind  first  one  of  the  motives  and  then 
the  other,  and  making  a  positive  choice  between  them.  On 
Barrett's  interpretation,  the  motives  are  effective  because 
they  appeal  to  certain  instinctive  or  habitual  and  social 
traits  in  the  man's  nature.  On  Michotte's,  the  final  de- 
terminant of  action  is  a  force  or  active  element  which 
serves  to  make  the  choice  and  release  the  act.  On  the 
second  alternative,  the  active  element  is  hard  to  describe, 
is  found  by  only  a  few  men  and  by  them  only  on  rare 
occasions.  Although  prominent  in  popular  discussions,  the 
observation  of  untrained  men,  who  constitute  the  chief  ad- 
vocates of  its  existence,  is  unrehable.  Much  of  the  feehng 
of  will  that  the  popular  mind  accepts  as  evidence  of  a  sep- 
arate faculty  is  made  up  of  strain  sensations,  which  even 
Michotte  would  not  regard  as  an  essential  part  of  his  vol- 
untary act.  Viewed  from  the  practical  side,  it  makes  very 
Httle  difference  whether  this  active  element  is  or  is  not  as- 
sumed. All  would  agree  that  when  the  will  acts,  it  acts  in 
the  light  of  the  motives;  it  is  an  expression  of  the  nature 
of  the  man;  and  that  in  turn  is  dependent  upon  his  in- 
stincts and  training,  his  immediate  purposes  and  general 


534        FUNDAMENTALS   OF  PSYCHOLOGY 

ideals.  The  only  question  remaining  is  whether  these  act 
directly  in  the  execution  of  the  movement,  or  whether  they 
act  first  upon  the  will,  and  that  in  turn  determines  the  act. 
In  view  of  the  uncertainty  as  to  whether  the  will  activity 
exists  and  what  it  is  like  if  it  exists,  it  seems  simpler  and 
safer  to  omit  it  as  superfluous,  and  to  assume  that  the  ob- 
served conditions  determine  action  directly.  On  that  con- 
clusion, 'will'  is  a  term  to  designate  the  whole  man  active, 
or  a  word  used  to  distinguish  between  automatic  acts  and 
those  that  imply  choice  and  are  controlled  by  the  system 
of  purposes.  It  does  not  necessarily  imply  any  new  and 
distinct  entity. 

The  Will  and  Freedom.  —  This  result  suggests  the  old 
problem  of  the  freedom  of  the  will,  and  it  may  be  consid- 
ered here,  in  spite  of  the  fact  that  it  is  at  present  regarded 
as  belonging  to  ethics  rather  than  to  psychology.  At  first 
sight  it  seems  a  logical  inference  that,  if  man  has  no  will, 
he  cannot  be  free.  This  defines  the  will  too  narrowly;  it 
would  restrict  it  to  the  something  that  we  could  not  find 
standing  between  the  motives  and  the  act  itself.  If  we 
regard  the  will  as  the  sum  of  the  conditions  which  lead  to 
action  or  to  spontaneous  action,  or  even  more  generally  as 
the  whole  man  active,  the  question  cannot  be  disposed  of 
so  summarily.  From  this  point  of  view,  the  answer  as  to 
whether  the  man  is  free  depends  very  largely  upon  how  we 
define  'the  man.'  We  have  seen  throughout  that  many  of 
the  determinants  of  all  mental  action,  and  particularly  of 
voluntary  action,  are  to  be  found  in  his  instincts,  in  the 
way  he  has  been  affected  by  education  and  by  the  society 
in  which  he  has  lived,  by  his  nature  and  nurture  in  the 
broadest  use  of  both  terms.  If  one  is  to  oppose  these  ex- 
ternal forces  to  the  man  himself,  a  good  case  could  be 
made  for  the  statement  that  the  man  is  largely  determined 


THE   WILL 


535 


by  forces  outside  of  himself.  But  if  one  make  the  division 
between  the  man  and  all  of  these  factors,  if  one  take  away 
from  the  man  all  that  he  has  learned,  all  the  controlling 
forces  of  society,  and  all  of  his  natural  endowments,  his 
instincts  and  innate  tendencies,  only  a  rag  of  a  man  would 
be  left;  most  that  is  peculiarly  himself  would  have  disap- 
peared. It  is  altogether  more  satisfactory  and  truer  to  the 
facts  to  regard  these  influences  as  included  in  the  man,  to 
think  of  him  as  in  part  at  least  the  product  of  his  heredity 
and  environment,  for  this  is  the  man  as  we  know  him.  To 
divide  the  controUing  forces  into  two  groups,  one  external, 
the  other  internal,  one  environmental,  the  other  personal, 
has  never  been  attempted;  and  no  two  psychologists  agree 
where  the  division  would  come.  Oppose  the  man  as  he  is, 
to  external  forces,  and  he  must  be  said  to  control  his  own 
acts.  They  are  the  expression  of  the  whole  man,  and  he 
is  free  to  do  as  he  chooses.  One  may  put  the  solution  of 
the  problem  in  another  way  by  asserting  that  man  is  free 
to  do  what  he  desires,  but  his  desires  are  the  outcome  of 
his  instincts  and  environment  and  over  these  he  has  little 
control.  In  other  words,  the  question  is  largely  one  of 
classifying  facts  and  of  defining  terms.  The  facts  them- 
selves are  accepted  by  all. 

In  practice,  acceptance  of  one  theory  or  the  other  makes 
little  difference.  What  one  generally  does  is  to  think  of 
one's  self  as  a  free  agent  in  every  respect,  and  of  every  one 
else  as  rigidly  determined  by  environment  and  education. 
It  is  only  when  one  takes  the  objective  attitude  toward 
one's  own  acts,  that  one  tries  to  trace  them  to  their  condi- 
tions. Probably  this  assumption  works  best  in  practice. 
The  new  tendency  to  regard  man  as  the  product  of  his  en- 
vironment has  led  to  improvement  in  social  conditions,  to 
the  recognition  that  mankind  in  the  mass  may  be  improved 


536        FUNDAMENTALS   OF  PSYCHOLOGY 

if  one  will  but  begin  with  remedying  the  fundamental  con- 
ditions of  living,  that  changing  his  environment  is  better 
than  talking  to  him.  Improvements  in  education,  in  hous- 
ing conditions,  and  all  the  multitude  of  laws  for  bettering 
the  environment  of  the  poor,  are  due  to  the  growing  tend- 
ency to  regard  the  environment  as  responsible  for  the  ac- 
tions of  others.  On  the  other  hand,  the  behef  in  one's  own 
freedom  probably  gives  added  initiative,  and  increased 
recognition  of  individual  responsibihty  that  would  be  lost 
were  one  to  think  of  one's  self  as  a  mere  Knk  in  the  world 
chain.  However,  the  instinct  of  self-assertion  is  too  strongly 
embedded  to  permit  acceptance  of  any  theory  to  change 
the  aggressive  individual  into  an  inert  one. 

Probably  the  difference  in  the  attitude  towards  crime 
and  the  criminal  more  clearly  represents  the  effects  of  the 
two  theories.  On  the  older  free-will  doctrine,  the  criminal 
was  altogether  responsible  for  his  acts.  He  would  or  he 
would  not  carry  out  each  act.  There  could  be  no  control 
of  crime,  because  no  one  could  tell  when  an  individual 
might  decide  to  commit  one.  The  other  theory  looks  upon 
the  criminal  as  the  product  of  his  heredity  and  of  his  en- 
vironment, in  much  the  same  way  that  a  sick  man  is  the 
victim  of  circumstances.  In  the  extreme  form,  the  whole 
problem  is  one  of  removing  the  causes  of  crime,  as  the 
control  of  health  is  one  of  removing  the  causes  of  disease. 
The  attitude  toward  punishment  changes  similarly.  If 
the  man  is  free  to  be  a  criminal  or  not  to  be,  the  only 
value  of  punishment  is  to  get  even,  to  measure  the  crime 
and  make  him  suffer  as  he  has  made  others  .suffer,  *an  eye 
for  an  eye.'  On  the  other  theory,  punishment  is  merely  a 
means  of  reform.  It  gives  the  criminal  a  motive  for  re- 
fraining from  crime,  it  may  give  him  a  chance  to  form  new 
habits,  or  even  to  learn  some  new  trade  or  obtain  some 


THE  WILL  537 

other  means  of  support  that  shall  make  crime  unnecessary. 
In  the  worst  cases,  it  is  a  protection  to  society  by  remov- 
ing the  criminal  to  a  place  where  he  can  do  no  harm.  In 
any  case  the  idea  of  vengeance,  essential  to  the  older  view, 
plays  no  part.  When  it  is  considered  that  a  large  percent- 
age of  criminals  are  mentally  deficient,  have  an  intelHgcnce 
no  greater  than  a  child  of  ten,  the  modern  theory  has  even 
more  weight.  The  final  outcome  of  the  two  theories  is  ap- 
proximately the  same;  but  the  methods  of  inflicting  the 
punishment  and  the  attitude  while  carrying  it  out  are  al- 
together different.  On  the  whole  it  may  be  said  that  the 
problem  of  the  freedom  of  the  will  has  been  outgrown 
rather  than  solved.  The  present  attitude  toward  the 
world  and  man's  place  in  the  world  leaves  no  room  for  the 
problem,  instead  of  deciding  which  solution  is  the  correct 

one. 

REFERENCES 

Ladd-Woodworth:    Principles    of    Physiological    Psychology, 

pp.  542-565- 
Ach:  Ueber  die  Willenstatigkeit  und  das  Denken. 
Swift:  Mind  in  the  Making. 
Bair:  The  Acquirement  of  Voluntary  Control.     Psych.  Review, 

Vol.  VIII,  pp.  474  ff- 
Woodworth:  Le  Mouvement. 


CHAPTER  XVIII 

WORK,   FATIGUE,  AND   SLEEP 

Very  important  for  the  practical  life  of  industry  and  even 
for  the  health  of  the  individual  is  the  problem  of  the 
natural  course  of  work,  particularly  the  length  to  which 
work  may  be  carried  before  the  individual  becomes  in- 
capable of  more  work,  or  will  suffer  injury  either  immedi- 
ately or  ultimately.  In  industry,  and  probably  in  mental 
work  too,  there  are  Hmits  beyond  which  one  cannot  work 
effectively.  Time  spent  in  work  would,  beyond  these 
limits,  much  better  be  spent  in  rest  or  recreation;  even  if 
one  considers  only  the  accomplishment  in  a  given  time,  with 
no  thought  of  the  effort  required,  or  the  ultimate  health  of 
the  worker. 

Work 

The  Curve  of  Accomplishment.  —  The  course  of  work, 
or  the  curve  which  indicates  the  accompHshment  at  differ- 
ent intervals  during  a  period  of  work,  is  fairly  well  made 
out  both  for  purely  mental  work  and  for  the  combination 
of  physical  and  mental  work  which  is  found  in  the  ordinary 
factory  procedure.  At  the  very  beginning  there  is  usually 
a  rapid  dechne  in  accompHshment.  This  is  followed  by 
a  gradual  rise  to  a  maximum  moderately  early;  and  from 
that  point  there  is  a  dechne  until  just  before  the  end,  when 
a  brief  rise  occurs  for  the  last  few  minutes.  If  rest  periods 
intervene,  they  are  followed  by  a  rise,  succeeded  by  a  fall 
at  a  more  rapid  rate  than  before  the  rest.  The  duration 
of  the  different  phases  varies  with  the  total  length  of  the 

538 


WORK 


539 


period  of  work,  with  the  individual,  and  with  the  character 
of  the  work.  In  one  or  two  instances  of  mental  work  under 
considerable  incentive,  there  was  no  appreciable  change  in 
the  curve.  In  one  in  which  mental  arithmetic  was  the 
work  used,  the  decrease  during  twelve  hours  of  continuous 
work  was  only  about  fifty  per  cent,  and  at  the  end  the  work 
was  at  a  rate  above  that  of  the  ordinary  individual. 

In  the  tests  of  mental  work  made  by  Kraepelin  and  his 
students,  of  two  hours'  duration,  the  point  of  highest  ac- 
comphshment  was  from  fifteen  to  forty-five  minutes  after 
the  work  began,  with  a  gradual  fall  to  the  end.  In  records 
of  output  of  work  in  various  factories,  the  high  point  seems 
to  be  between  nine  and  ten  o'clock,  when  the  work  begins 
at  eight ;  then  there  is  a  fall  until  noon ;  and  after  the  noon 
hour  an  increase;  with  a  decrease  to  the  end  of  the  day. 
As  further  evidence  that  there  is  a  somewhat  regular  curve 
of  capacity  in  the  day's  work  in  the  factory,  is  the  time  of 
occurrence  of  the  maximum  number  of  accidents.  An  acci- 
dent is  due  as  often  to  mental  as  to  physical  fatigue.  Failure 
to  attend  or  to  remember,  or  lack  of  judgment  in  estimating 
the  position  of  knives  or  other  parts  of  a  machine,  is  more 
frequently  the  cause  of  an  injury  than  mere  physical 
fatigue.  Accidents  show  a  regular  increase  until  eleven 
in  the  morning,  after  which  the  curve  is  constant  or  shows 
a  very  slight  decrease  in  the  last  hour  in  the  morning.  It 
falls  after  the  noon  hour  to  about  the  same  level  as  in  the 
first  hour  in  the  morning,  and  rises  rapidly  and  continuously 
during  the  afternoon. 

We  have  then  in  the  course  of  work,  particularly  work 
that  demands  mental  activity,  as  almost  all  work  does, 
a  quick  fall  for  the  brief  period  at  the  beginning,  then  a 
gradual  increase  in  accomplishment  for  a  time,  followed 
again  by  a  decrease  that  is  checked  only  by  a  short  rise  at 


S40        FUNDAMENTALS   OF  PSYCHOLOGY 

the  end,  if  the  worker  knows  when  the  end  is  to  be.  A 
rest  of  sufficient  duration  is  followed  by  increased  output, 
and  then  ensues  a  more  rapid  decrease  than  in  the  period 
before  the  end. 

Analysis  of  the  Curve  of  Work.  —  In  the  analysis  of  this 
standard  curve  of  work  it  is  assumed  that  the  capacity 
at  a  given  time  is  determined  by  a  number  of  cooperating 
independent  factors.  The  one  most  frequently  mentioned 
is,  fatigue,  which  is  assumed  to  increase  with  the  time  spent 
in  work.  The  second,  practice,  counteracts  fatigue,  since 
it  also  increases  capacity  as  work  increases  in  a  somewhat 
regular  course.  Practice  increases  more  rapidly  at  first, 
and  then  less  rapidly.  Practice  is  alhed  to  habit  as  an 
adjustment  of  the  nervous  system  to  a  new  situation,  and 
constitutes  what  we  call  skill.  It  is  assumed  to  reach  a 
maximum  at  some  time,  although  it  is  probable  that  new 
conditions  of  work  or  a  new  attitude  towards  work  may 
produce  an  improvement  even  after  long  periods  of  training. 
It  can  be  said,  however,  that  practice  will  make  work  more 
easy  and  effective,  that  it  increases  rapidly  at  first  and  then 
more  and  more  slowly  as  work  is  continued. 

The  initial  fall  and  terminal  increase  are  due  to  a  tem- 
porary incentive.  The  individual  begins  with  a  firm  in- 
tention of  doing  his  best,  and  does  so  for  a  few  strokes. 
This  special  incentive  wears  away  quickly,  and  with  it 
there  is  often  a  fall  in  output  immediately  after  work  begins. 
At  the  end  there  is  a  similar  speeding  up  to  make  a  good 
showing  for  the  finish.  This  is  not  necessarily  conscious, 
but  the  very  fact  that  the  end  is  in  sight  serves  as  an 
incentive  and  speeding  up  takes  place  automatically,  just 
as  the  goal  in  a  race  calls  out  a  final  increased  effort.  A 
fourth  factor  is  inertia.  In  most  types  of  work  it  takes 
a  little  time  to  reach  the  best  speed;  and  when  once  started 


FATIGUE  541 

work  is  continued  at  approximately  the  same  rate.  This 
is  most  evident  in  the  fact  that  when  the  work  is  inter- 
rupted by  a  rest,  some  time  is  required  to  reach  the  same 
speed  as  before  the  interruption.  It  makes  a  shorter 
rest  within  hmits  more  effective  in  restoring  efficiency  than 
a  longer  one. 

Fatigue 

Is  Fatigue  Real?  —  The  most  important  of  these  factors 
is  fatigue.  By  fatigue  we  mean  a  reduction  in  the  capacity 
for  doing  work  which  comes  as  a  result  of  work.  This 
definition  is  open  to  criticism  from  the  fact  that  not  all 
work  seems  to  be  followed  by  a  reduction  in  capacity  even 
for  doing  the  same  kind  of  work.  KraepeHn  explained 
this  as  due  to  the  counteracting  effect  of  practice  and 
inertia.  Others  have  held  at  times  that  there  is  no  mental 
fatigue,  but  that  the  working  individual  merely  becomes 
bored,  not  tired,  that  the  central  nervous  system  does  not 
lose  capacity  with  work.  The  results  of  Aral  ^  are  cited 
as  evidence  that  mental  work  may  go  on  indefinitely 
without  noticeable  diminution  in  output.  We  can  probably 
reconcile  the  facts  adduced  in  favor  of  the  two  views  by 
assuming,  as  there  is  good  reason  to  do,  that  organically 
work  produces  a  lessened  capacity  in  the  organism,  but 
that  this  is  automatically  compensated  for  by  extra  effort. 
This  keeps  the  individual  working  at  about  the  same  speed, 
and  possibly  with  just  as  few  mistakes  in  spite  of  reduced 
physical  capacity.  The  awareness  of  fatigue  is  itself  an 
incentive  that  in  many  individuals  spurs  to  new  effort. 
In  tliis  respect  fatigue  is  just  hke  distraction;  and  like 
distraction  it  may  at  times  over-compensate,  so  that  an 
individual  works  even  more  rapidly  when  fatigue  has  set 

1  Arai,  Mental  Fatigue:  Columbia  University  Contributions  to  Education 
No.  54. 


542 


FUNDAMENTALS   OF  PSYCHOLOGY 


in.  That  fatigue  is  a  real  factor  is  evident  from  the  fact 
that  occasionally  a  worker  will  keep  up  the  same  speed 
for  a  considerable  period  and  then  will  stop  suddenly  with 
what  seems  to  be  a  collapse.  Dodge  has  shown  this  in 
connection  with  fatigue  of  eye  muscles,  and  we  find  some 
evidence  of  it  in  the  daily  work,  particularly  in  diseased 
individuals.  It  must  be  said,  however,  that  ordinarily 
the  disagreeableness  of  work  after  fatigue  is  pronounced  is 
a  sufficient  safeguard  against  carrying  work  to  the  point  of 
collapse. 

While  fatigue  is  a  real  accompaniment  of  mental  as  well 
as  of  physical  work,  the  fact  that  fatigue  does  not  increase 
regularly  with  the  amount  of  work  makes  it  difficult  to 
determine  what  the  condition  of  the  individual  is  at  any 
time  as  regards  fatigue.  One  may  obtain  a  general  in- 
dication from  the  amount  of  work  done  as  compared  with 
the  average  accomplishment,  or  by  introducing  some: 
special  test  or  standardized  task  that  shall  be  closely 
related  to  the  work  being  done.  The  objection  to  the 
latter  is  that  one  can  nearly  always  under  incentives  spur 
one's  self  to  a  maximum  rate  for  a  brief  period,  and  the 
test  becomes  an  unsatisfactory  criterion  of  the  condition. 
Dr.  Lewis  has  found  indication  that  the  glycogen  content 
of  the  blood  is  increased  during  fatigue;  and  Dr.  Griffitts 
and  the  writer  have  found  indication  of  a  lowered  blood 
pressure  after  severe  mental  work.  It  is  highly  desirable 
to  find  some  such  test  of  condition  that  shall  be  independent 
of  work  done,  that  may  be  used  to  determine  when  the 
individual  has  worked  enough.  On  the  whole,  it  seems 
assured  that  there  is  a  real  fatigue  as  a  result  of  mental 
work.  Whether  one  can  define  fatigue  as  the  reduced 
capacity  for  doing  work  as  a  result  of  work  or  not,  is  com- 
plicated by  the  fact  that  diminished  physical  capacity  is 


FATIGUE  543 

compensated  for  by  greater  effort.  If  capacity  is  under- 
stood as  a  physical  capacity,  only  indirectly  indicated  by 
accomplishment,  it  may  stand.  It  is  at  least  as  satis- 
factory as  any  formula  that  can  be  suggested. 

The  Physiological  Nature  of  Fatigue.  —  When  we  turn 
to  ask  what  the  cause  of  fatigue  may  be,  we  must  approach 
the  problem  from  the  physiological  side.  The  first  studies 
of  fatigue  were  made  on  the  muscle  and  nerve  of  a  frog. 
If  a  muscle  with  the  motor  nerve  that  excites  it  be  dis- 
sected out  of  a  frog,  and  hung  so  that  the  muscle  supports 
a  lever  that  will  write  upon  a  drum,  the  amount  of  the 
contraction  will  be  recorded  upon  the  drum.  If  the  nerve 
be  stimulated,  the  muscle  will  contract;  as  the  stimulation 
is  continued  the  contractions  become  shorter  and  shorter 
until  they  finally  cease.  The  causes  of  fatigue  in  this 
simple  system  are  found  first  in  the  breaking  down  of  the 
point  of  connection  between  nerve  and  muscle,  the  end- 
■olate.  This  is  shown  by  the  fact  that  after  the  muscle  can 
no  longer  be  stimulated  through  the  nerve,  it  will  still 
respond  when  stimulated  directly. 

Continued  direct  stimulation  of  the  muscle  will  com- 
pletely fatigue  the  muscle.  This  indicates  that  there  is  a 
real  fatigue  of  the  muscle  proper.  The  nature  of  this 
change  is  due  in  part  to  the  accumulation  of  products  of 
degeneration,  as  can  be  seen  from  the  fact  that  after  the 
muscle  has  stopped  acting  once  through  fatigue,  it  will 
respond  again  in  almost  full  amount  after  it  has  been 
thoroughly  washed  in  a  dilute  solution  of  salt.  There  is 
also  exhaustion  of  the  stored  nourishment  in  the  tissue, 
but  this  seems  to  come  later  than  the  inhibition  of  the 
capacity  for  action,  due  to  the  accumulation  of  waste 
oroducts.  In  addition  to  the  waste  products  that  accumu- 
late in  the  muscle  itself,  investigations  of  animals  working 


544        FUNDAMENTALS   OF  PSYCHOLOGY 

as  wholes  indicate  that  toxins  appear  in  the  blood  and 
may  be  carried  to  any  part  of  the  body  and  affect  tissues 
of  all  kinds.  An  old  experiment  of  Mosso  showed  that 
blood  transfused  from  a  fatigued  dog  to  a  rested  one  pro- 
duced in  him  many  of  the  effects  of  fatigue.  While  later 
experiments  do  not  altogether  confirm  the  Mosso  method, 
other  methods  do  indicate  an  accumulation  of  toxins  in  the 
blood  as  a  result  of  continued  work.  The  toxic  effects 
seem  to  be  diminished  or  overcome  by  the  secretions  of 


Fig.  07.  —  Changes  in  the  nucleus  as  a  result  of  fatigue.  (.4)  and  (B)  are  both 
from  the  spinal  ganglion  of  a  cat.  (A)  shows  the  resting  condition,  (B)  a  cell 
after  electrical  stimulation  of  its  nerve  for  five  hours.  The  nuclei  in  (B)  may  be 
seen  to  be  much  smaller  and  to  be  very  irregular  in  outline.  (From  "American 
Text-book  of  Physiology,"  after  Hodge.) 


adrenal  glands.  Animals  in  whom  the  glands  are  removed 
indicate  a  much  greater  effect  of  work,  and  are  also  more 
influenced  by  injections  of  fatigue  products  than  are  normal 
animals.  This  may  explain  why  Dr.  Lewis  found  an  in- 
crease in  glycogen  in  the  blood  following  mental  work. 
It  is  possible  that  the  adrenal  secretion  nulhfies  fatigue 
indirectly  by  increasing  digestion  and  stimulating  the  hver 
to  an  increased  secretion  of  glycogen. 

Fatigue  of  Central  Cells.  —  In  the  body  as  a  whole  one 
more  factor  is  at  work,  and  this  is  the  possible  exhaustion 


FATIGUE  545 

of  the  nerve  cell.  Hodge  found  in  a  bee  that  after  a  full 
day's  work,  the  nucleus  of  the  ganglion  cells  was  very  much 
reduced  in  size,  and  the  walls  of  the  nucleus  were  irregular 
in  shape  as  if  collapsed,  as  compared  with  the  same  cells 
in  the  morning.  Electrical  stimulation  of  the  cells  from 
the  spinal  cord  of  the  cat  for  five  hours  produced  much  the 
same  effect.  These  changes  in  the  cell  bodies  of  nerves, 
the  accumulation  both  in  muscles  and  in  the  blood  of  waste 
products  which  act  as  poisons,  the  exhaustion  of  the  tissues 
and  of  the  muscles  together  constitute  the  physical  changes 
in  fatigue.  These  effects  do  not  all  act  to  reduce  the 
capacity.  In  the  isolated  muscle,  even,  the  first  effect  of 
fatigue  is  to  produce  unusually  large  contractions.  Ap- 
plication to  the  muscle  in  small  amounts  of  waste  substances 
from  another  muscle  increases  the  amount  of  contraction 
even  with  constant  stimulus;  and  the  products  of  the 
muscle  itself  have  the  same  effect.  Fatigue  products  first 
increase  the  excitability  of  a  muscle,  and  then  diminish 
and  finally  destroy  it. 

Consciousness  of  Fatigue.  —  On  the  mental  side,  con- 
sciousness of  physical  fatigue  is  marked  by  sensations  of 
pain  or  at  least  of  discomfort  from  the  muscles.  The 
lactic  acid  and  other  chemicals  released  by  repeated  con- 
tractions apparently  stimulate  the  nerves  of  pain  in  the 
muscles  directly  and  give  rise  to  the  sensations.  More 
general  feehngs  of  lassitude  may  be  due  to  the  reduced 
tonus  of  the  muscles  or  to  the  slowness  with  which  muscles 
respond  to  stimulation.  That  there  are  complexes  of 
sensations  which  go  with  the  condition  we  know  as  fatigue 
is  evident  to  every  one.  The  immediate  sensations  are 
probably  to  be  found  in  the  excitations  of  pain  nerves  in 
the  muscles.  The  remainder  is  probably  an  inference 
from  the  reduced  capacity  for  action.     It  has  been  sug- 


546        FUNDAMENTALS   OF  PSYCHOLOGY 

gested  that  mental  fatigue  is  largely  an  inhibition  of  action 
from  the  distracting  effect  of  these  sensations.  This  may 
account  for  part  of  the  reduced  efficiency,  although,  as  was 
seen,  distraction  also  tends  to  increase  efficiency  on  occasion. 
Mental  Fatigue.  —  What  may  constitute  mental  fatigue 
apart  from  bodily  fatigue,  is  not  as  yet  altogether  agreed 
upon.  Mental  work  has  always  an  incidental  physical  ac- 
companiment. Muscles  are  always  active  in  some  degree. 
That  they  are  sufficiently  active  to  account  for  the  effects 
of  mental  work  is  extremely  unlikely.  Certainly  mere 
thinking  on  an  abstruse  problem  is  harder  work  than  a 
game  of  golf,  for  example,  which  must  involve  vastly  more 
muscular  contraction.  Some  considerable  acti\dty  of  the 
cortical  neurones  must  be  involved  in  thinking,  but  we 
have  only  indirect  evidence  of  the  amount  of  change  in 
energy  or  chemical  decomposition  involved,  and  these  point 
in  opposite  directions.  Atwood  could  find  no  increase  in 
the  bodily  metabolism  during  mental  work.  Dodge,  on 
the  contrary,  found  that  mental  work  had  about  the  same 
eft'ect  on  the  circulation  as  physical  work  of  average  in- 
tensity. Merely  opening  the  eyes  and  passively  observing 
a  room  produced  a  change  equivalent  to  that  produced  by 
Hfting  a  pound  weight;  and  hard  reading  was  found  to  be 
the  equivalent  of  a  genuflection.  Fatigue  might  be  due  to 
exhaustion  of  the  neurones  directly,  or  it  rnight  be  due  to 
the  waste  products  that  are  discharged  into  the  circula- 
tion and  reach  the  muscles  and  other  parts  of  the  brain. 
No  one  has  as  yet  demonstrated  the  existence  of  either 
change.  The  nearest  approach  is  the  discovery  by  Dr. 
Lewis  of  increased  amounts  of  glycogen  in  the  blood  as  an 
accompaniment  of  mental  work.  The  indirect  evidence  of 
mental  fatigue  is  found,  first  in  the  feeling  of  lassitude  that 
follows  upon  mental  work,  second  in  the  decrease  of  the 


FATIGUE  547 

amount  of  work  as  time  passes,  third  in  the  after-effects 
of  long-continued  excess  of  mental  work  in  inducing  loss  of 
weight,  and  the  various  physical  and  mental  symptoms 
that  accompany  what  is  called  a  nervous  breakdown.  Alto- 
gether these  suffice  to  indicate  the  reality  of  mental  fatigue 
and  its  general  similarity  to  physical  fatigue. 

Bodily  Accompaniments  of  Fatigue.  —  If  we  consider 
the  action  of  fatigue,  mental  or  physical,  in  the  conditions 
of  everyday  Ufe,  we  must  assume  that  each  bit  of  work 
has  the  effect  of  decreasing  the  nourishment  stored  in  the 
tissues,  of  increasing  waste  products  in  the  tissues  them- 
selves and  in  the  blood,  and  that  if  it  be  muscular  work 
continued  for  a  long  time  on  one  muscle  it  may  decrease 
or  destroy  the  connections  at  the  end  plate,  and  finally  ex- 
haust the  nucleus  of  the  cells.  The  first  effect  of  these 
changes  is  probably  to  increase  the  irritability  of  the 
muscle,  which  increases  its  capacity.  These  processes, 
through  the  excitation  of  nerves  in  the  muscles,  produce 
reflexly  an  increase  in  the  rate  of  the  heart,  and  of  respira- 
tion, thus  supplying  more  oxygen  to  the  red  blood  corpus- 
cles, and  a  larger  flow  of  blood,  which  both  increases  the 
nourishment  at  the  service  of  the  muscle  and  washes  the 
waste  products  out  more  quickly.  After  a  time  the  ad- 
renal glands  are  affected,  and  these  increase  the  supply  of 
glycogen  from  the  liver  and  also  affect  the  activity  of  the 
circulatory  system.  For  a  considerable  period  these  auto- 
matically induced  processes  compensate  for  the  extra  work. 
The  capacity  of  the  organism  is  increased  to  keep  up  with 
the  demand. 

All  these  increased  activities  make  a  demand  upon  the 
reserve;  and  while  the  reserve  is  sufficient  to  keep  the  out- 
put at  a  maximum  over  a  long  period  or  even  to  increase 
it,  it  is  alway?.  at  the  expense  of  extra  effort.    In  the  long 


548        FUNDAMENTALS   OF  PSYCHOLOGY 

run  there  must  come  an  end.  Unless  the  demand  is  very 
great,  the  pain  of  aching  muscles  and  the  other  discomforts 
of  exhaustion  bring  the  work  to  a  stop.  It  is  possible 
under  great  necessities  to  continue  until  exhaustion  is 
complete  and  sleep  or  other  forms  of  unconsciousness  en- 
sue to  put  an  end  to  the  work  and  permit  recovery  to  be- 
gin. Only  very  rarely,  as  in  a  strenuous  mihtary  cam- 
paign, or  the  work  of  a  mother  with  a  sick  child  and  the 
necessity  of  earning  a  Hving,  do  we  see  this  stage  reached 
in  practice.  Usually  boredom  or  the  unpleasant  sensations 
that  accompany  fatigue  induce  one  to  rest,  long  before  this 
stage  is  reached.  This  is  still  more  the  case  with  mental 
fatigue.  Here  the  fatigue  from  one  position,  if  one  is  writ- 
ing, or  the  poor  quahty  of  work  will  make  the  further  ef- 
fort useless,  or  will  furnish  an  excuse  for  turning  to  a  more 
pleasant  undertaking.  In  mental  work,  also,  the  effects  of 
the  work  seem  at  times  to  act  as  a  stimulant.  When  writ- 
ing or  much  interested  late  at  night,  work  seems  to  go 
faster  and  to  be  pleasanter  than  in  the  earher  part  of  the 
day,  when  fatigue  should  be  much  less.  That  this  feehng 
is  not  an  indication  of  work  without  fatigue  is  evident 
from  the  after-effects,  the  Kkelihood  of  a  sleepless  night 
and  of  an  incapacity  for  work  the  next  day.  Both  mental 
and  physical  work  and  the  combination  of  the  two  that  is 
seen  in  industry  bring  with  them  a  decreased  capacity  for 
work,  although  that  may  be  concealed  by  the  compensat- 
ing increased  activity.  Work  beyond  a  certain  point  is  in- 
jurious to  the  individual  in  that  it  shortens  the  period  of 
activity,  and  shows  its  effect  in  the  diminished  output  of 
the  next  day.  It  is  a  disadvantage  in  industry  for  the 
day-to-day  accomplishment. 

Fatigue  in  Industry.  —  Numerous  practical  experiments 
have  shown  that  lessening  the  hours  of  work,  even  with  no 


FATIGUE  549 

reduction  in  wages,  is  a  prolitable  change  for  employer  and 
worker  alike.  The  Zeiss  works  in  Jena,  numerous  muni- 
tions factories  under  the  control  of  the  war  board  in  Great 
Britain,  and  several  cases  in  America  show  that  reduction 
from  a  ten-  to  an  eight-hour  day  could  be  made  with  an 
actual  increase  in  the  output.  We  have  no  right  to  dog- 
matize as  to  the  optimum  working  period.  Too  much  de- 
pends upon  the  kind  of  work,  the  good  will  of  the  workers, 
and  other  conditions  which  are  either  not  directly  under 
control  or  are  not  known  as  yet  to  make  it  possible  to  be 
certain  as  to  the  correct  hours  for  any  industry,  to  say 
nothing  of  industry  in  general.  For  our  purposes,  the  evi- 
dence is  sufficient  to  indicate  that  there  is  a  Kmit  of  work- 
ing time  beyond  which  it  is  not  profitable  to  go.  Probably 
this  is  on  the  average  near  the  eight-hour  day.  Slower 
work,  spoiled  products,  accidents,  and  the  gradual  deteri- 
oration in  the  operatives,  set  a  definite  limit  to  the  profit- 
able hours  of  work. 

The  Limits  of  Effective  Work.  —  It  is  difificult  to  deter- 
mine exactly  where  the  limit  hes.  The  output,  we  have 
seen,  is  no  infallible  criterion,  because  when  under  the  in- 
fluence of  strong  incentives,  work  may  continue  undimin- 
ished when  fatigue  is  severe.  The  sensations  and  other 
direct  mental  signs  are  also  far  from  infaUible.  In  many 
cases,  again  under  incentives,  one  feels  that  work  is  a 
pleasure,  when  a  sleepless  night,  or  a  reduced  capacity  next 
day,  will  be  the  penalty  for  continuing.  On  the  other 
hand,  one  frequently  feels  httle  like  working  when  per- 
fectly capable  of  doing  it.  One  may  have  a  stale  feeling  in 
the  morning,  spend  some  time  in  wondering  whether  one 
really  ought  to  work  that  day,  or  even  fear  that  the  work  if 
done  will  be  below  standard,  and  then  find  when  one  actually 
warms  up  to  it  that  quaHtyand  quantityare  normal  orbetter. 


550        FUNDAMENTALS  OF  PSYCHOLOGY 

It  would  be  highly  desirable  to  discover  some  index  of 
the  condition  of  the  individual  that  might  be  used  by  em- 
ployer, or  teacher,  or  physician,  to  determine  the  point 
where  work  should  stop.  Attempts  have  been  made  to 
obtain  one.  The  writer  has  experimented  with  the  time 
that  one  may  see  a  faint  Hght,  and  has  found  that  the  time 
of  visibiUty  changes  with  the  amount  of  work  done.  With 
Dr.  Grifhtts  he  recently  found  indications  that  there  was 
a  reduced  blood  pressure  after  mental  work.  Lewis,  as 
was  said,  had  found  an  increase  in  the  glycogen  in  the 
blood.  While  the  increased  glycogen  is  probably  a  com- 
pensation induced  by  fatigue,  a  sufficient  amount  or  a  de- 
crease after  increase  might  be  made  a  sign  of  the  point 
where  work  should  stop.  Changes  in  heart  rate,  in  blood 
pressure  sitting  and  standing,  have  been  suggested.  One 
must  probably  find  a  fatigue  index  in  some  of  these  indi- 
rect measures  rather  than  in  the  output  or  the  sensations, 
or  any  of  the  more  direct  changes.  Long  study  will  be 
necessary  to  determine  at  just  what  point  in  the  develop- 
ment of  any  one  of  these  indices,  work  should  stop.  Ob- 
servation of  the  changes  in  the  sign  chosen  in  connection 
with  the  after-effects  of  fatigue  and  the  capacity  for  work 
over  a  long  period  must  be  exhaustive  before  a  useful  de- 
termination may  be  made. 

General  Rules  for  Effective  Work.  —  Meanwhile  certain 
general  rules  can  be  given  which  are  helpful  in  the  ar- 
rangement of  work.  One  must  not  expect  to  avoid  fatigue. 
Fatigue  as  a  group  of  sensations  from  the  muscles  or  a  feel- 
ing of  lassitude  from  long  mental  work  is  an  inevitable 
accompaniment  of  all  activity.  Only  when  it  becomes  ex- 
cessive is  it  even  a  signal  to  stop.  As  a  tendency  to  an  ex- 
haustion of  the  tissues  even,  it  is  still  not  injurious,  for  the 
deficiency  is  quickly  restored  by  rest,  and  use  is  essential 


F/VriGUE  551 

to  growth,  or  even  to  health.  y\ll  that  one  can  ask  is  that 
fatigue  should  be  kept  witliin  the  limits  that  permit  of 
quick  recovery  during  the  same  day  if  possible,  and  will 
certainly  give  complete  restoration  after  a  night  of  rest. 
How  long  this  shall  be  for  the  individual  must  be  deter- 
mined empirically.  Usually  the  effective  working  period  is 
well  within  the  Kmits  that  are  demanded  by  health.  Prob- 
ably within  tliis  effective  time  are  the  Umits  set  by  the  dis- 
comfort of  sensation,  or  boredom,  or  the  conventions  of  the 
hours  that  shall  be  devoted  to  work.  In  practice  few  stu- 
dents overwork,  and  those  who  do  are  the  weaker  ones. 
For  industry,  the  hours  are  set  by  the  length  of  day  most 
profitable  to  the  employer.  This,  when  all  the  facts  are 
understood,  will  be  found  well  within  the  physiologically 
determined  Kmits  of  capacity. 

The  Economical  Periods  of  Work.  —  The  most  econom- 
ical period  of  work  is  that  in  which  one  obtains  all  the  ad- 
vantages of  continued  work  without  going  on  to  the  point 
of  fatigue.  It  is  of  course  impossible  to  give  any  general 
rules  that  will  apply  to  all  kinds  of  work  and  to  all  people. 
How  much  work  may  be  done  depends  upon  the  nature  of 
the  work  and  upon  the  strength  of  the  individual.  The 
fact  that  one  does  more  after  working  for  a  Httle  time  than 
when  one  first  begins  holds  universally.  How  long  one 
should  continue  after  the  effects  of  fatigue  are  greater  than 
the  benefits  of  practice,  depends  upon  the  kind  of  work  and 
the  practical  necessities  for  its  completion.  Fatigue  itself 
is  not  to  be  avoided,  for  the  lesser  degrees  wear  off  in  a 
short  time  and  are  entirely  overcome  by  a  night's  sleep. 
The  poor  work  that  results  when  fatigue  is  too  great  makes 
effort  unprofitable,  and  the  after-effects  in  the  form  of 
overwork  may  have  such  serious  results  as  to  put  a  pre- 
mium upon  avoiding  them  at  all  reasonable  cost. 


552        FUNDAMENTALS   OF  PSYCHOLOGY 

The  Best  Period  for  Rest.  —  To  know  how  long  to  rest 
between  periods  of  work  is  as  important  as  to  know  when 
to  stop.  Results  of  experiments  indicate  that  the  length  of 
the  rest  that  should  be  introduced  between  the  periods  of 
work  depends  upon  the  length  of  the  previous  work  and 
upon  the  character  of  the  work.  The  rest  should  be  long 
enough  to  permit  recovery  from  fatigue,  but  not  so  long  as 
to  lose  the  mental  momentum.  After  long  periods  of  work, 
two  hours  or  more,  the  most  advantageous  intermission  is 
approximately  fifteen  minutes;  for  relatively  short  periods 
five  minutes  has  proved  itself  most  satisfactory.  Longer 
periods  waste  too  much  time,  and  cause  a  loss  of  inertia 
and  of  practice  that  is  not  compensated  for  by  recovery 
from  fatigue.  Shorter  intermissions  merely  cause  loss  of 
inertia  without  any  compensating  rest.  In  severe  physical 
work  in  industry  it  has  been  found  as  important  to  insist 
upon  proper  and  sufficient  periods  of  rest  as  upon  sufficient 
periods  of  work.  In  Taylor's  first  experiment  in  efficiency 
management,  which  consisted  in  a  study  of  the  best  meth- 
ods of  lifting  heavy  pigs  of  iron,  it  was  found  that  if  the 
men  followed  their  natural  bent,  working  with  the  pros- 
pect of  a  bonus,  they  would  work  too  continuously,  and  it 
was  necessary  to  prescribe  rest  periods  which  should  be 
rigidly  observed,  if  the  most  work  was  to  be  accomplished 
in  a  day.  Mental  work  requires  similar  «est  periods  for 
the  maximimi  performance,  but  the  best  periods  for  the 
different  types  and  degrees  of  work  have  not  been  deter- 
mined accurately. 

Change  of  Work  No  Rest.  —  Several  facts  that  have 
been  suggested  by  experiments  are  contrary  to  the  com- 
mon assumptions  of  many  people.  For  example,  it  is  be- 
lieved usually  that  one  may  rest  through  change  of  work, 
—  that  if  one  has  been  tired  by  mental  work  of  one  sort  it 


FATIGUE  553 

is  not  necessary  to  rest  altogether,  but  by  turning  to  some- 
thing else  one  may  become  rested  through  the  change. 
The  one  important  investigation  on  this  point  indicates 
that  the  everyday  assumption  is  not  in  harmony  with  the 
facts.  An  hour's  work  learning  nonsense  syllables,  fol- 
lowed by  a  half  hour's  practice  on  mental  arithmetic,  with 
a  return  to  the  nonsense  syllables,  rests  one  no  more  than 
a  continued  period  of  nonsense  syllables.  This  is  on  the 
assumption  that  learning  nonsense  syllables  is  no  more 
difhcult  than  mental  arithmetic.  If  one  turns  from  a  more 
difficult  to  an  easier  task,  one  will  of  course  not  be  so  tired 
as  if  one  had  continued  with  the  more  dif^cult.  So  far  as 
these  results  can  be  accepted,  it  seems  that  all  sorts  of 
mental  fatigue  are  of  the  same  kind,  and  that  it  is  not  pos- 
sible to  rest  one  function  while  exercising  another.  There 
is  so  much  in  common  between  the  different  mental  opera- 
tions that  all  become  tired  together.  It  is  possible  that 
the  commonly  accepted  opinion  to  the  contrary  is  due  to 
the  greater  interest  one  may  have  in  a  new  task.  One  or- 
dinarily turns  from  a  task  only  when  obstacles  have  pre- 
sented themselves  or  when  for  some  reason  the  work  has 
become  uninteresting.  It  is  possible  that  the  greater  in- 
terest in  the  new  work  and  consequent  greater  effective- 
ness are  mistaken  for  recovery  from  fatigue. 

Mental  and  Physical  Fatigue  One.  —  Very  similar  is  the 
attitude  toward  the  problem  of  the  relation  between  men- 
tal and  physical  fatigue.  It  is  generally  beheved  that  one 
may  rest  from  mental  work  while  exercising,  but  experi- 
ments indicate  that  capacity  for  mental  work  is  decreased 
by  physical  work,  if  it  is  too  difficult.  If  one  takes  a  vigor- 
ous run  or  other  severe  exercise  between  two  periods  of 
the  same  sort  of  work,  as  in  the  experiments  mentioned 
above,  the  capacity  for  mental  work  is  diminished  rather 


554        FUNDAMENTALS   OF  PSYCHOLOGY 

than  increased.  Here  as  before  the  effect  will  depend  upon 
the  severity  of  the  task.  If  the  exercise  be  mild,  one  will 
rest  relatively,  just  as  one  does  during  less  difficult  mental 
work.  In  fact,  the  whole  question  of  work  and  fatigue  is 
relative,  as  one  never  rests  absolutely  except  during  sleep, 
and  even  then  there  is  merely  gain  of  repair  over  waste, 
not  absolute  quiescence  of  all  functions.  The  identity  of 
mental  and  physical  fatigue  has  been  demonstrated 
many  times,  both  that  mental  work  induces  physical  fa- 
tigue and  that  physical  work  induces  mental  fatigue.  One 
cannot  do  severe  mental  work  effectively  after  a  hard  day 
of  physical  labor,  and  experiments  show  that  one  is  less 
capable  of  physical  labor  after  hard  mental  work.  This 
general  identity  of  mental  and  physical  work  and  fatigue  is 
being  recognized  by  the  physician.  A  patient  suffering 
from  overwork  as  a  result  of  too  much  study  or  worry  is  no 
longer  advised  to  take  much  exercise,  but  is  put  to  bed  or 
given  very  little,  easy  exercise.  Of  course  this  does  not 
imply  that  exercise  is  not  beneficial  in  health.  Exercise  is 
essential  to  the  development  and  health  of  the  body,  and 
needs  no  justification.  One  should  not  expect  to  be  able  to 
work  immediately  after  exercise,  but  in  the  long  run  the 
effects  of  exercise  are  beneficial. 

Morning  and  Evening  Workers.  —  Another  interesting 
result  of  recent  investigations  is  that  there  are  daily 
rhythms  of  capacity  for  work,  that  every  one  has  a  certain 
part  of  the  day  during  which  he  has  greater  capacity.  Ac- 
cording to  one  authority,  men  divide  naturally  into  morn- 
ing and  evening  workers.  The  one  group  are  at  their  best 
early  in  the  morning,  the  other  group  do  not  reach  their 
full  capacity  until  toward  evening,  —  the  amount  and  ac- 
curacy of  their  work  increases  steadily  through  the  day. 
It  has  not  been  determined  whether  the  difference  is  in- 


FATIGUE  555 

nate  or  the  result  of  habit;  but  in  an  adult  accustomed  to 
mental  work,  one  habit  or  the  other  is  always  readily  dem- 
onstrated, even  if  the  individual  himself  is  unaware  of  it. 
Evidently  one  should  take  advantage  of  the  daily  rhythm 
by  devoting  the  best  part  of  the  day  to  the  more  difficult 
tasks.  There  are  also  minor  ups  and  downs  in  capacity 
during  the  day  which  may  be  confused  with  rest  and  fa- 
tigue in  experiments. 

General  Remarks  on  Work.  —  It  should  be  added  that 
the  measurements  of  fatigue  upon  which  these  statements 
rest  are  derived  from  ordinary  routine  work  under  no  par- 
ticular incentive  other  than  to  do  one's  best.  It  is  certain 
that  a  sufficiently  strong  desire  would  at  any  stage  have 
brought  the  rate  of  work  back  to  the  maximum,  at  least 
for  a  little  time.  While  the  amount  of  work  that  will  be 
accompHshed  depends  very  largely  upon  the  incentive,  it 
does  not  follow  that  fatigue  is  not  real  and  a  factor  to  be 
considered  in  the  arrangement  of  the  day's  routine.  The 
results  that  have  been  given  hold  for  the  course  of  ordi- 
nary work  where  the  incentive  is  constant  and  not  particu- 
larly strong.  If  the  incentive  is  increased,  the  absolute 
times  given  would  all  be  increased,  but  the  relative  values 
would  still  remain  approximately  the  same.  There  would 
still  come  a  time  when  the  amount  and  accuracy  of  the 
work  would  be  reduced  to  a  point  where  work  did  not  pay. 
Work  done  willingly  and  cheerfully  under  suitable  incen- 
tives is  apparently  less  fatiguing  in  the  long  run  than  a 
smaller  amount  accomplished  under  unfavorable  condi- 
tions. One  may  even  agree  with  James  that  in  moments 
of  exaltation  one  may  perform  at  a  rate  far  above  the  or- 
dinary level  without  permanent  injury,  and  at  the  same 
time  accept  the  results  of  experiments  under  ordinary  con- 
ditions as  a  guide  for  daily  hfe. 


556        FUNDAMENTALS   OF  PSYCHOLOGY 

Sleep 

The  natural  consequence  of  fatigue,  and  closely  related 
to  it  in  theory,  is  sleep.  Curiously  enough  in  spite  of  the 
frequency  of  occurrence  of  the  phenomenon,  sleep  is  one  of 
the  least  understood  of  the  psychological  and  physiological 
processes.  We  know  relatively  little  of  the  reasons  why 
one  goes  to  sleep,  or  what  takes  place  when  one  does  go  to 
sleep.  As  in  fatigue,  one  may  develop  a  circulatory  the- 
ory, a  chemical  theory,  a  central  nervous  theory,  and  a 
general  reaction  theory,  not  to  mention  attention  theories 
and  a  dissociation  theory.  It  was  long  held  that  sleep 
could  be  explained  by  a  decrease  in  the  circulation  of  the 
blood  in  the  brain,  which  rendered  the  brain  less  capable  of 
action,  and  so  caused  unconsciousness.  It  is  hardly  likely 
that  the  reduction  in  circulation  should  be  so  complete;  if 
it  were,  there  would  be  no  rebuilding  of  the  tissue.  Dr. 
Shepard  and  others  have  shown  that  there  is  an  increase 
rather  than  a  decrease  in  the  volume  of  the  brain  in  sleep. 
The  only  suggestion  of  confirmation  of  the  theory  is  that 
the  walls  of  the  blood  vessels  of  the  brain  are  very  much 
relaxed  in  sleep,  so  that  waves  of  respiration  are  very  much 
greater  than  in  the  waking  state.  This  is  more  likely  to  be 
an  effect  than  a  cause  of  sleep. 

Chemical  Theories  of  Sleep.  —  The  chemical  theory  is 
that  the  products  of  fatigue  accumulate  in  the  central  cor- 
tical cells  and  reduce  or  destroy  temporarily  their  capacity 
for  action.  Pieron  has  results  which  lead  him  to  beHeve 
that  a  toxin  is  developed  in  the  blood  by  loss  of  sleep 
which  is  different  from  that  developed  by  fatigue.  When 
blood  from  an  animal  that  has  been  kept  awake  for  a  long 
period  is  injected  into  the  fourth  ventricle  of  the  brain  of 
another  animal  of  the  same  species,  it  shows  all  of  the  signs 


SLEEP  557 

of  sleepiness  of  the  animal  from  which  the  fluid  is  taken. 
Fatigue  products  from  the  muscles  do  not  show  the  same 
effect.  Pieron's  belief  is  that  the  toxin  of  sleep  is  devel- 
oped by  the  action  of  the  cells  of  the  cortex,  and  might 
constitute  a  specific  result  of  mental  work  for  which  we 
were  seeking  in  an  earlier  section. 

Nervous  Theory  of  Sleep.  —  The  central  nervous  system 
theory  was  connected  with  the  synapses.  In  sleep  the  nerve 
currents  run  very  slowly,  and  this  indicates  increased 
resistance  at  the  synapse.  One  early  theory  was  that  sleep 
was  due  to  the  withdrawal  of  the  dendrites,  in  the  same  way 
that  the  amoeba  draws  in  its  processes  when  asleep.  In 
animals  killed  by  an  anaesthetic  the  dendrites  were  retracted 
in  this  way.  The  amoeba  theory  of  the  synapses  has  been 
given  up,  more  because  it  was  difficult  to  understand  why 
an  animal  should  be  aroused  from  sleep  by  outside  stimuli 
than  because  it  did  not  harmonize  with  anatomical  observa- 
tions. The  theory  explains  sleep,  but  would  permit  only 
spontaneous  waking. 

Sleep  an  Instinct.  —  The  most  recent  theory  is  that 
sleep  is  an  instinctive  reaction  to  definite  sets  of  stimuli. 
Several  analogies  may  be  developed  which  are  in  line  with 
this  assumption.  The  first  is  the  long  hibernation  or  winter 
sleep  of  many  animals.  This  seems  to  be  altogether  or 
largely  a  response  to  the  season,  or  to  temperature  and 
other  changes  that  come  with  the  seasons.  Another  re- 
sponse of  quiescence  to  a  positive  stimulus  is  the  death- 
feigning  instinct  of  many  feeble  animals,  such  as  the 
opossum,  and  the  young  of  the  terns.  To  a  strong  stimulus, 
they  respond  by  loss  of  the  capacity  for  movement,  which 
sometimes  is  accompanied  by  loss  of  muscular  tonus. 
Claparede  some  years  ago  and  Rivers  recently  have  sug- 
gested in  slightly  different  forms  that  sleep  is  a  response 


558        FUNDAMENTALS   OF  PSYCHOLOGY 

of  a  similar  character,  that  serves  to  make  possible  the 
recuperation  of  the  individual.  During  sleep  cessation  of 
all  activity,  and  increased  circulation  in  the  cortex,  and 
possibly  in  other  important  organs,  stop  use  and  supply 
materials  for  rebuilding  tissues. 

To  say  that  sleep  is  an  instinct  does  not  explain  it  until 
we  can  discover  what  the  nature  of  the  reaction  may  be 
and  what  causes  it.  The  stimulus  for  sleep  varies  much 
under  different  conditions.  In  most  cases  it  is  a  response 
that  recurs  at  approximately  the  same  time  of  day.  In 
this  animals  differ  widely.  Some  instinctively  respond  by 
sleep  to  the  coming  of  darkness,  others  to  the  coming  of  day. 
The  difference  is  altogether  instinctive.  In  man  the  instinct 
is  subordinated  to  habit,  and  the  time  of  approach  of  the 
response  and  the  length  of  sleep  vary  with  the  earlier  Kfe 
and  occupation  of  the  individual.  In  addition  the  imme- 
diate stimulus  may  be  presence  of  feehngs  of  fatigue,  but. 
on  the  other  hand  too  much  fatigue  may  prevent  sleep. 
Monotonous  stimuH  are  also  frequently  followed  by  sleep. 
Absence  of  stimulation  acts  as  a  monotonous  stimulus.  All 
stimuli  for  sleep  work  best  when  accompanied  by  sugges- 
tion. If  one  expects  to  sleep,  sleep  is  almost  certain,  unless 
other  circumstances  are  unfavorable.  Excessive  fatigue 
will  also  finally  result  in  sleep,  but  can  be  fought  off  volun- 
tarily, or  under  the  influence  of  strong  stimuli,  for  a  long 
time.  Animals  kept  awake  by  strong  stimuli  will  die  after 
a  few  days.  Loss  of  sleep  is  more  quickly  fatal  than  is 
starvation.  Fatigue  seems  to  be  an  inducing  condition,  and 
sleep  is  more  and  more  likely  as  fatigue  advances,  provided 
other  conditions  are  favorable.  It  seems  to  be  a  contribut- 
ing condition  rather  than  the  immediate  cause,  until  it 
becomes  very  intense.  The  final  collapse  from  exhaustion 
seems  to  be  not  quite  the  same  as  the  normal  sleep  in 


SLEEP  559 

moderate  degrees  of  fatigue.  It  is  more  like  an  intoxication. 
The  observed  phenomena  of  sleep  seem  to  combine  most 
if  not  all  of  the  factors  that  have  been  suggested  as  the 
causes  of  sleep.  Measurements  of  the  course  of  sleep  show 
that  there  is  a  constant  increase  in  the  depth  of  sleep  as 
measured  by  the  strength  of  the  stimulus  required  to  waken 
the  sleeper,  during  the  first  hour  and  a  half.  After  that 
there  is  a  diminution  up  to  the  time  of  waking.  Accompany- 
ing this  there  is  a  decrease  in  blood  pressure  during  the  first 
part  and  a  rise  in  the  latter  part.  On  the  nervous  side,  the 
reduced  stimulability  has  been  interpreted  as  due  to  an 
inhibition  of  the  cortical  centres;  it  has  also  been  regarded 
as  a  mark  of  dissociation,  for  certain  of  the  phenomena  of 
sleep  walking  and  dreams  seem  alUed  to  hypnotism,  and 
similar  processes,  that  are  explained  as  due  to  dissociation. 
One  may  think  of  sleep,  then,  as  a  reaction  in  which  the 
central  nervous  system  has  its  activity  inhibited,  and  the 
action  of  the  lower  centres  is  checked,  which  carries  with 
it  changes  in  circulation  and  respiration  and  prevents  the 
acti\ity  of  muscles  and  glands.  The  net  result  is  a  state 
in  which  recuperation  is  possible.  It  is  also  a  self-terminat- 
ing process.  As  the  tissues  are  restored,  and  toxins  removed 
from  the  tissues  and  from  the  circulation,  the  susceptibility 
of  the  central  nervous  system  is  restored,  and  any  stimulus 
is  more  hkely  to  induce  the  activity  of  the  cortex  which 
brings  with  it  the  release  of  inhibition  and  restoration  of 
the  functions  of  circulation  and  respiration. 

REFERENCES 

Lee:  The  Human  Machine. 

Muscio:  Lectures  in  Industrial  Psychology,  pp.  45-88. 

Myers:  The  Mind  and  Work.     Chapter  II. 

Shepard:  The  Cerebral  Circulation  in  Sleep. 

H.  Pieron:  Le  probleme  physiologique  du  sommeil. 


CHAPTER  XrX 

THE  SELF 

In  our  ordinary  life  and  in  much  of  scientific  psychological 
discussion  frequent  use  is  made  of  the  term '  self ' .  For  popu- 
lar thought  the  most  important  part  of  consciousness  and 
of  the  world  as  a  whole  is  found  in  the  'I.'  To  it  practically 
everything  is  referred.  It  is  regarded  as  the  effective  agent 
in  most  of  the  acts  of  the  individual,  and  is  the  source  of 
most  of  his  emotions.  A  notion  that  has  so  large  a  share  in 
our  mental  life  must  be  closely  examined  and  if  possible 
explained.  We  must,  as  psychologists,  take  the  same  atti- 
tude toward  it  as  toward  the  concrete  experiences  so  far 
examined.  We  must  seek  to  determine  how  far  it  is  open  to 
examination  as  a  mental  state,  what  effect  it  has  on  be- 
havior, and  how  the  idea  must  have  developed  to  the  form 
that  it  takes  at  present.  It  is  for  us  one  phenomenon  among 
many,  in  spite  of  the  central  position  that  it  holds  in  popular 
discussion.  The  occasion  for  the  development  of  the  self 
comes  from  the  practical  needs  for  a  distinction  between 
the  individual  and  others,  and  between  the  individual  and 
the  outside  world.  To  represent  these  distinctions,  con- 
cepts have  gradually  grown  up  in  much  the  same  way  that 
concepts  of  external  things  develop,  and  they  are  Hke  them 
in  every  respect.  Each  has  some  mental  content,  and 
represents  a  large  number  of  distinctions  and  processes  not 
present  in  the  idea. 

560 


THE   NATURE   OF    THE   SELF  561 

The  Nature  of  the  Self 

The  Occasions  for  the  Self-concepts.  —  We  recognize 
not  one  concept  of  the  self  but  many,  corresponding  to  the 
dififerent  occasions,  to  the  different  ways,  in  which  the  outer 
must  be  opposed  to  the  inner,  and  to  the  different  lines  of 
division  at  which  one  may  be  marked  off  from  the  other. 
Three  fairly  general  Hnes  of  demarcation  may  be  drawn. 
One  is  between  the  man  as  a  whole,  including  the  body,  and 
the  other  individuals  in  society.  This  is  the  self  as  con- 
sidered in  law  and  in  most  of  the  more  popular  objective 
discussions.  A  second  line  of  di\dsion  develops,  as  the  theo- 
retical interests  become  dominant,  between  the  body  and 
the  mental  states  or  consciousness.  Finally,  a  third  notion 
of  the  self  tends  to  mark  off  the  more  spontaneous  and 
purposive  acts,  those  that  are  foreseen  and  consented  to, 
as  over  against  the  acts  induced  by  external  forces  or  even 
by  reflexes,  —  the  acts  that  are  intended,  from  those  that 
are  not  intended.  The  first  we  may  call  the  physical  self, 
the  second  the  subjective  self,  the  third  the  effective  self. 
It  must  be  insisted  that  these  lines  of  division  cannot  be 
sharply  drawn  and  that  they  are  not  consistent  from 
moment  to  moment.  At  any  particular  time  we  are  inter- 
ested only  in  one  distinction  and  have  no  reference  to  the 
others.  While  there  are  many  gross  references  and  many 
occasions  on  which  it  is  desirable  to  unite  the  three  concepts 
into  a  single  one,  they  can  best  be  discussed  separately  at 
first,  and  then  united  so  far  as  is  possible  in  a  common 
notion.  In  considering  these  concepts,  one  must,  as  in  all 
cases,  distinguish  between  the  conscious  element  used  in 
representing  the  self,  and  the  meaning,  —  the  thing  or 
processes  represented  by  that  concept. 

The   Physical   Self.  —  The  centre  of  reference  of   the 


562        FUNDAMENTALS  OF  PSYCHOLOGY 

physical  self  seems  to  be  the  body,  partly  as  it  is  seen  in 
the  field  of  vision,  partly  as  it  is  reconstructed  on  the  basis 
of  mirror  images  and  photographs  and  from  the  references 
of  friends.  The  meaning  of  this  physical  self  is  very  much 
wider.  It  is  used  to  refer  to  the  body,  together  with  many 
of  the  man's  immediate  possessions,  —  garments  and 
adornments,  and  an  ever-widening  group  of  properties. 
The  'physical  self  gradually  comes  to  be  indistinguishable 
from  the  'physically  mine.'  Houses  and  lands,  friends  and 
position,  all  of  the  things  that  one  must  struggle  with  other 
men  to  retain,  come  to  form  part  of  the  physical  'me.' 
This  physical  self  derives  much  of  its  meaning  from  com- 
parison with  others.  One  tends  to  see  one's  self  in  relation 
to  others  about.  The  man's  picture  of  himself  and  of  his 
possessions  always  involves  a  comparison  with  others  and 
with  the  ideals  that  these  set  for  his  own  attainment.  The 
wealth  of  the  individual,  rich  and  poor  ahke,  has  increased 
enormously  in  the  last  century,  but  nevertheless  the  line 
is  quite  as  sharply  drawn  now  as  ever  before,  since  the 
relative  differences  are  approximately  the  same.  Similarly, 
one's  opinion  of  one's  physical  self  in  the  narrowest  sense 
varies  with  the  individuals  with  whom  one  comes  in  contact. 
One  feels  one's  self  quite  a  man  among  small  men,  while 
there  is  a  decided  shrinking  when  with  men  of  large  stature. 
One  can  imagine  how  different  GulUvero's  impression  of 
himself  must  have  been  when  in  Lilliput  from  what  it  was 
among  the  Brobdingnagians.  This  first  concept  represents 
the  man  to  himself  as  a  man  among  men.  It  is  the  self  in 
the  most  practical,  popular  sense. 

The  Subjective  Self.  —  The  second  concept  that  repre- 
sents the  self  as  opposed  to  the  body  is  of  much  less  general 
appUcation,  is  of  value  in  fact  only  in  connection  with  more 
theoretical  problems.    The  imaginal  centre  of  the  concept  is 


THE    NATURE   OF   THE   SELF  563 

less  definite;  probably  kinaesthetic  and  organic  sensations 
offer  what  little  there  is  of  actual  content.  Sometimes  there 
may  be  a  picture  of  the  self,  —  as  the  spirit  of  the  savage, 
or  the  ghost  of  the  ignorant, — a  bodily  self  with  the  physical 
characteristics  subtracted,  so  far  as  that  is  possible.  This 
seems  relatively  rare  among  psychologists,  and  others  have 
not  reported  their  results  in  sufficient  numbers  to  afford 
much  ground  for  generalization.  Usually  one  is  satisfied 
with  the  sensations  of  strain  in  the  head  or  in  the  chest  as  an 
embodunent  of  the  notion  of  the  self.  Its  applications,  too, 
are  relatively  few.  One  pictures  one's  self  as  rising  above 
bodily  limitations  in  ill  health;  one  opposes  this  self  to 
the  sense  organs  and  their  imperfect  reports  of  the  world. 
In  psychology  it  is  made  to  include  consciousness  as  opposed 
to  the  activities  of  the  nervous  system  which  are  purely 
mechanical.  It  is  also  of  value  in  explaining  dreams,  in 
which  the  body  seems  to  be  in  one  place  while  the  spirit  is 
in  another.  When  we  attempt  to  determine  to  what  place 
sensations  are  ascribed,  there  is  httle  agreement  even  for 
a  single  sense.  The  skin  marks  the  boundary  of  the  self 
for  touch ;  one  thinks  of  one's  self  as  receiving  impressions 
at  the  surface  and  not  at  some  point  back  in  the  brain.  For 
hearing  and  sight  the  fine  of  division  is  not  so  definite. 
Most  refer  the  sensations  to  the  object  in  the  outside  world; 
and  the  hearing  and  seeing  self  is  given  no  definite  place. 
Organic  sensations,  particularly  the  strain  sensations  that 
come  with  effort,  are  assigned  to  the  self  as  opposed  to  the 
body.  On  the  sensory  side,  then,  while  every  one  would 
assert  that  mind  and  body  are  to  be  distinguished  and  that 
the  *I'  is  on  the  self  side,  the  line  of  division  is  very  vague. 
In  most  cases  one  would  deny  any  of  the  seats  that  might 
be  suggested  for  the  processes  without  being  able  to  assign 
a  better.    It  would  not  even  be  a  matter  of  agreement  that 


564        FUNDAMENTALS   OF  PSYCHOLOGY 

the  self  in  this  sense  included  all  of  consciousness;  nor, 
granting  that,  exactly  how  much  it  did  include.  Obviously, 
this  second  concept  corresponds  to  a  real  need  in  psychologi- 
cal discussions,  but  equally  obviously  the  concept  is  not  at 
present  and  probably  cannot  be  very  clear  cut,  either  in  its 
image  or  in  the  limits  that  it  makes  between  self  and  not- 
self. 

The  Active  Self.  —  The  third  concept  of  the  effective 
or  dynamic  self  represents  a  more  real  need  both  in  psy- 
chology and  in  practical  life.  In  nearly  every  one  of  the 
processes  we  have  considered,  something  has  been  left  un- 
settled in  the  explanation.  The  final  presupposition  upon 
which  explanation  of  each  was  based  had  many  similar 
elements  in  each  of  the  processes  discussed,  and  different 
theories  sought  an  explanation  of  each  of  the  more  important 
processes  in  terms  of  some  other.  In  attention,  first,  it  was 
seen  that  there  was  a  final  factor  which  was  characterized 
by  the  feeling  of  effort  reduced  in  part  to  sensations  of 
strain,  the  condition  of  which  was  found  in  social  pressure. 
The  resulting  attention  was  classed  as  voluntary.  The 
same  factors  were  at  work  in  the  control  of  associations, 
and  were  later  seen  to  be  factors  which,  when  present,  in- 
creased the  rate  at  which  associations  were  formed.  In 
the  emotions  it  was  found  necessary  to  assume  some  tend- 
ency toward  an  end,  some  purpose  that  must  be  aided 
or  hindered  before  emotions  could  appear.  Finally,  in 
action  it  is  necessary  and  usual  to  distinguish  simpler 
movements,  that  come  under  the  head  of  reflex,  instinct,  or 
habit,  from  those  that  seem  to  depend  upon  wider  knowl- 
edge and  more  fully  conscious  purpose.  Each  of  these 
has  something  in  common.  Voluntary  attention  was 
explained  by  the  social  instinct;  emotion  seemed  dependent 
upon  purposive  activity  of  some  sort;  action  is  commonly 


THE   NATURE   OF   THE   SELF  565 

explained  by  attention  to  an  idea  or  an  end.  Nor  is  the 
interrelation  limited  by  these  statements.  Many  authori- 
ties would  explain  movement  in  terms  of  feeling;  others, 
feeling  in  terms  of  movement;  still  others,  attention  in 
terms  of  movement;  others  again,  attention  in  terms  of 
feeling,  just  as  feeling  and  movement  are  explained  by  some 
in  terms  of  attention.  The  common  elements  in  all  of 
these  processes  and  the  last  term  in  the  explanation  of  each 
are  often  called  the  self. 

The  self  in  this  sense  has  practically  no  new  mental 
processes  to  represent  it.  One  may  think  of  it  equally  well 
as  the  physical  self  or  a  ghostly  self.  The  mental  content 
is  indifferent  to  the  meaning.  The  only  sensational  ele- 
ment that  is  at  all  a  general  concomitant  is  the  mass  of 
strain  sensations  so  frequently  mentioned  as  constituting 
the  feehng  of  effort.  These  are  taken  to  serve  as  an  in- 
dication of  activity  rather  than  as  a  direct  revelation  of  the 
self.  In  the  attempt  to  analyze  the  factors  which  determine 
the  course  of  this  activity,  we  again  have  little  to  say. 
Our  first  reduction  to  social  pressure  proves,  when  seen  in 
the  light  of  our  knowledge  of  instinct,  to  reduce  largely  to 
a  social  instinct  guided  by  knowledge  obtained  from  the 
society  in  which  the  man  has  lived.  The  original  instinct 
we  found  in  discussing  emotions  developed  into  a  system 
of  ideals,  and  these,  as  they  became  more  active,  constituted 
the  purposes  of  the  individual.  The  study  of  action  offered 
no  new  contributions  to  our  explanation;  action  was  an 
outcome  of  ideals  and  purposes  acting  in  selection.  There 
was  found  no  new  impelling  force,  nor  even  any  new  quality 
or  mental  state.  Study  of  the  self  adds  nothing  new.  As 
a  man  studies  his  own  self,  he  is  aware  of  the  fact  that  he  is 
acting  or  deciding,  but  he  gets  almost  no  light  as  to  what 
the  process  consists  in.     If  he  studies  another,  he  can 


566        FUNDAMENTALS   OF  PSYCHOLOGY 

trace  certain  factors  that  seem  to  play  a  part  in  making 
that  individual  decide  as  he  does,  but  neither  observation 
of  one's  self  nor  of  another  can  show  directly  what  the 
determining  activity  is.  Curiously  enough,  tracing  the 
conditions  tends  to  discover  the  basis  of  the  activities  that 
are  beUeved  to  be  pecuHarly  characteristic  of  the  self  in 
society.  The  more  intimately  personal  the  act,  the  more 
objective  are  its  conditions,  the  more  external  the  forces 
that  bring  it  about. 

In  each  of  these  more  active  processes,  one  feels  that 
there  is  something  that  must  be  explained  in  terms  of  fac- 
tors that  cannot  be  definitely  formulated.  The  tendency 
is  always  to  bring  in  some  other  simple  process  as  the  basis 
of  the  explanation,  hence  the  reference  from  one  process 
to  another  among  mental  states.  But,  when  one  sees 
that  one  can  complete  the  circle  and  come  no  nearer  the 
explanation  in  one  group  than  in  any  other,  it  is  obvious 
that  going  around  the  circle  has  not  furthered  the  explana- 
tion. Two  alternatives  remain  open.  One  may  assume 
either  that  some  highest  process  controls  all  the  others,  or 
that  there  are  common  elements  in  each;  and  then  seek 
to  determine  what  they  are.  The  popular  mind  takes  the 
first  of  the  alternatives,  —  assumes  the  self  as  a  prime 
determinant,  and  makes  it  the  final  force  in  all  spontaneous 
action.  Since,  however,  this  is  in  reality  no  explanation 
but  merely  a  tagging  of  the  facts  that  are  to  be  explained, 
it  is  more  important  to  determine  the  elements  common 
to  each.  This  we  may  find  in  the  developed  ideals  and 
purposes,  which  in  turn  are  to  be  referred,  first  to  instincts, 
then  to  the  ideals  of  society  taken  over  by  the  individual 
largely  by  virtue  of  the  social  instinct  —  the  instinct  to 
seek  approval  —  and  then  tested  and  confirmed  by  his  own 
individual  experience.     If  other  factors  enter,  they  cannot 


THE   NATURE   OF  THE   SELF  567 

be  traced,  either  in  the  introspection  of  the  agent,  or  by  a 
study  of  the  behavior  of  others.  In  the  complexity  of  the 
conditions  that  act  upon  the  individual  we  are  not,  however, 
in  a  position  to  assert  that  no  others  are  effective  at  any 
point. 

The  Social  Factors  in  the  Self  Concept.  —  These  three 
concepts  of  the  self  tend  to  fuse  into  a  single  one  in  which 
something  of  each  is  retained,  and  are  more  or  less  har- 
monized into  a  unitary  whole.  The  representative  self 
has  something  of  the  body,  something  of  the  mental  as 
opposed  to  the  bodily,  more  of  the  strain  processes  that 
mark  it  as  active.  The  concept  is  ordinarily  employed 
to  distinguish  between  the  self  and  society,  between  the 
'I'  and  the  'You,'  or,  objectively,  between  the  character- 
istics of  the  different  individuals  with  whom  I  come  in 
contact,  who  must  be  used  in  the  accompUshment  of  my 
ends,  or  who  use  me  in  the  attainment  of  theirs.  With 
this  there  is  a  marked  effect  of  the  hfe  in  society.  Both 
the  static  and  the  d)niamic  features  of  the  self  are  ap- 
preciated only  in  terms  of  others  about.  One  has  an  idea 
of  one's  own  peculiarities  only  in  comparison  with  others. 
One's  notion  of  one's  self  as  a  whole  is  largely  an  image  of 
the  self  as  it  is  reflected  in  the  consciousness  of  others. 
When  a  man  is  among  men  of  smaller  attainments,  or 
smaller  possessions,  he  expands;  when  he  is  with  men  of 
larger  accomplishments  or  reputation  or  possessions,  he 
shrinks  just  as  evidently.  Much  of  this  idea  of  the  self 
depends,  not  upon  actual  ability  and  possession,  but  upon 
the  imagined  attitude  of  others.  A  man  becomes  accus- 
tomed to  act  as  if  he  were  of  more  than  ordinary  importance, 
society  takes  him  at  face  value,  and  he  may  go  for  years  or 
even  through  Hfe  without  having  the  notion  corrected  either 
for  himself  or  for  others.     On  the  other  hand,  a  few  rebuffs 


568        FUNDAMENTALS   OF  PSYCHOLOGY 

to  a  sensitive  individual  will  repress  his  self  in  his  own  eyes 
and  prevent  any  self-assertion.  If  he  has  high  ability,  it 
may  go  for  years  without  being  discovered.  Society  makes 
its  judgment  of  a  man  in  part  from  his  own  actions;  and 
these  in  turn  depend  in  some  measure  upon  the  estimate 
he  thinks  society  puts  upon  him.  The  process  is  a  cyclical 
one.  The  individual's  estimate  of  himself  is  what  he  be- 
lieves to  be  society's  estimate  of  him.  On  the  other  hand, 
society's  estmiate  of  the  man  is  very  largely  colored  by 
his  estimate  of  himself  and  his  consequent  bearing.  The 
way  in  which  the  individual  pictures  himself  and  the  esti- 
mate of  his  personal  capacity  are  largely  derived  from  the 
attitude  of  society  toward  him,  just  as  many  of  the  forces 
that  control  his  active  life  are  merely  an  expression  of  the 
society  in  which  he  lives. 

The  Emotions  of  Self.  —  The  activities  and  processes 
that  develop  the  notion  of  self  are  found  very  largely  in 
the  emotional  group.  What  we  called  the  more  com- 
plicated emotions,  those  which  come  from  the  interaction 
of  the  purposes  of  the  individual  with  the  environment, 
are  largely  social  in  character.  The  opposition  is  most 
often  from  other  men,  and  the  emotion  is  usually  ascribed 
to  an  expanding  or  shrinking  of  the  self.  In  fact,  in  much 
of  our  daily  life,  the  only  reason  for  making  use  of  the 
notion  of  the  self  is  to  picture  the  origin  and  the  immediate 
source  of  the  emotion.  We  are  concerned  with  the  self 
only  in  moments  of  struggle  and  the  consequent  success  or 
defeat.  In  periods  of  quiet  contemplation  of  external 
objects  or  even  in  the  unhindered  manipulation  of  things, 
we  are  little  aware  of  the  self.  With  opposition,  particularly 
from  other  men,  the  complex  of  emotions  comes  into  play. 
We  have  the  self-assertion  of  effort,  the  elation  of  victory, 
the  self-depreciation  of  defeat.     That  these  emotions  are 


THE   NATURE   OF   THE    SELF  569 

always  of  a  social  character  is  seen  in  the  fact  that  when 
one  performs  a  difhcult  feat  when  alone,  there  is  always 
a  thought  of  what  some  one  else  might  think;  and  the 
pleasure  in  the  success  comes  largely  from  the  background 
of  realization  that  it  is  better  than  could  have  been  done 
by  one's  rival.  The  onlooker  is  always  present  in  thought 
if  not  in  reality,  and  the  resultant  emotion  is  determined 
by  the  way  the  action  would  be  viewed  by  him  rather  than 
by  any  absolute  standard. 

These  self-regarding  emotions  constitute  the  core  of  the 
idea  of  the  self.  The  character  of  these  emotions  seems 
to  depend  upon  the  relation  between  the  ambitions  of  the 
individual  and  his  actual  accomplishments.  James  puts 
it  in  the  statement  that  self-esteem  equals  success  divided 
by  pretensions.  When  pretensions  are  large,  success  small, 
self-esteem  is  slight;  as  success  grows  or  ambitions  diminish, 
self-esteem  or  self-complacency  is  increased.  Self-esteem, 
too,  is  only  affected  when  success  or  failure  comes  in  some 
field  in  which  the  ambition  of  the  individual  hes.  A  scholar 
may  very  well  content  himself  with  little  of  the  worldly 
goods,  may  even  regard  wealth  as  somewhat  vulgar,  since 
he  has  never  set  himself  towards  its  attainment.  The 
wealthy  man  of  affairs  returns  the  compliment  by  saying 
he  can  buy  the  services  of  a  scientist  much  more  cheaply 
than  he  can  the  advice  of  a  financial  expert,  —  that  learn- 
ing is  a  drug  in  the  market.  Each  is  satisfied  with  his 
own  position,  with  his  own  self,  as  he  has  never  attempted 
to  extend  the  self  in  the  field  of  the  other.  But  when  men 
of  affairs  come  into  rivalry  in  the  same  field,  the  self  of  the 
one  is  humiUated  as  the  other  attains  what  he  has  himself 
sought. 

These  emotions,  or  the  conditions  that  he  behind  them, 
not  merely   determine   how   the   individual   shall   regard 


570        FUNDAMENTALS  OF  PSYCHOLOGY 

himself,  but  also  play  a  very  large  part  in  deciding  the 
degree  of  effectiveness  of  the  individual.  The  way  in  which 
the  self  is  regarded  determines  the  attitude  toward  the 
problems  of  life,  and  this  in  turn  is  an  important  factor  in 
the  success  or  failure  of  the  individual.  The  character  of 
the  individual,  viewed  either  from  within  or  from  without, 
is  closely  related  to  his  self-esteem. 

The  man  who  has  succeeded  and  lacks  a  sense  of  pro- 
portion or  the  saving  sense  of  humor  becomes  self-conceited. 
He  can  no  longer  remove  his  mental  gaze  from  contempla- 
tion of  his  own  capacities  and  of  past  successes,  nor  can  he 
avoid  expressing  this  appreciation  of  himself,  nor  conceal 
his  expectation  that  others  will  express  their  appreciation 
of  that  position.  A  child  who  is  always  the  centre  of  the 
approving  household  develops  an  exaggerated  notion  of  his 
own  importance,  and  his  early  success  in  business  or  scholar- 
ship not  infrequently  sets  an  attitude  of  self-satisfaction 
that  cannot  be  disturbed  even  by  later  failures  and  rebuffs. 

More  striking  is  the  expectation  of  failure  and  conse- 
quent lowering  of  ambitions  that  comes  with  crushing  de- 
feat. A  man  of  middle  age  who  suddenly  finds  his  system 
of  ambitions  thwarted  and  all  of  the  accumulations  of  pre- 
vious successes  swept  away,  seems  to  lose  not  merely  all 
of  his  ambitions,  all  of  his  self-respect,  but  also  the  capacity 
for  forming  new  purposes.  The  self  disappears  or  is  pro- 
foundly altered  with  the  despair  that  follows.  Numerous 
members  of  the  drifting  colonies  of  ne'er-do-wells  of  our 
large  cities  have  been  brought  to  their  position  by  some 
such  catastrophe.  The  man  of  means  who,  at  first  confident, 
self-assertive,  and  persistent,  loses  his  wealth  through  some 
mischance,  and  fails  in  the  first  few  efforts  to  reestabHsh 
himself,  comes  to  mistrust  himself  and  all  his  ventures,  — 
becomes  vacillating.     Others  lose  confidence  in  him,  and 


THE   NATURE   OF    THE    SELF  571 

he  either  decides  that  nothing  is  worth  while,  takes  a  care- 
free attitude  toward  the  world  and  attempts  nothing,  or 
falls  into  despair  and,  while  his  ambitions  are  retained, 
gives  up  hope  of  realizing  them.  In  brief,  the  system  of  ends 
feeds  on  success  and  grows  as  each  ambition  is  realized, 
but  shrinks  and  finally  disappears  with  repeated  failure. 
Happy  is  the  man  whose  ambitions  are  not  too  different 
from  his  capacities  and  to  whom  environment  is  sufficiently 
favorable  to  permit  the  realization  of  ambitions  in  sufficient 
degree  to  give  constant  encouragement,  without  too  great 
expansion  of  the  notion  of  his  capacity  and  importance. 

The  self  is  in  this  sense  an  outcome  of  the  emotions  which 
arise  when  the  system  of  aims  receives  a  shock,  or  attains 
one  of  the  subordinate  steps  toward  an  end  or  the  end  itself, 
although  the  emotions  are  in  many  cases  referred  to  the  self 
as  the  cause.  At  bottom,  the  two  processes  are  probably 
one.  The  self  is  a  concept  that  serves  to  explain  both  the 
emotions  that  originate  from  the  progress  toward  ends  and 
also  the  purposes  themselves.  Here  again  we  seem  to  be 
going  around  in  a  circle.  Where  we  seek  the  self,  we  find 
only  expressions,  only  processes  that  have  needed  a  self 
to  explain  them,  rather  than  a  real  self.  On  the  other  hand, 
when  we  seek  the  explanation  of  certain  of  the  more  funda- 
mental emotions,  we  are  said  to  discover  evidence  of  the 
self,  or  at  least  a  reference  to  the  self.  In  other  words, 
wherever  we  seek  the  self,  we  find  something  else,  but  when- 
ever we  are  seeking  an  explanation  of  spontaneous  or  pur- 
posive action,  we  find  that  we  need,  or  at  least  wish  we  might 
have,  a  self. 

To  bring  together  the  results  of  our  investigation,  the 
self  is  a  group  of  concepts  originally  developed  to  represent 
the  different  Hues  of  division  between  the  man  and  others, 
between  the  mental  and  physical  processes,  and  between 


572        FUNDAMENTALS   OF  PSYCHOLOGY 

the  more  mechanical  and  the  more  spontaneous  forms  of 
action.  The  different  concepts  are  frequently  fused,  at 
least  in  part,  into  a  single  concept  which  becomes  repre- 
sentative of  the  system  of  purposes  as  they  control  actions, 
which  gives  rise  to  emotions  and  serves  to  designate  the 
directing  forces  in  the  more  compHcated  mental  processes. 
This  concept  is  the  point  of  reference  for  all  our  self -regarding 
ambitions,  it  is  the  self  we  are  depressed  about  and  the  self 
that  we  exult  over.  Nevertheless  it  must  not  be  assumed 
that  something  corresponding  to  this  self  need  be  found  by 
introspection.  Just  as  space,  regarded  as  a  concept,  was 
needed  to  explain  certain  of  the  ways  in  which  we  saw 
objects  and  the  possibihties  of  movement,  so  the  concept 
of  the  self  is  merely  a  way  we  have  of  representing  to  our- 
selves the  immediate  facts  found  in  the  emotional  and  the 
active  life,  in  the  Ufe  of  decision.  Examination  gives  us 
nothing  more  than  does  contemplation.  We  can  analyze 
the  way  in  which  we  perceive  space  relations  into  certain 
elements,  we  can  show  why  we  need  the  concept  of  space, 
but  we  do  not  expect  to  find  anything  more  by  any  means. 
Similarly  with  the  self,  we  can  point  to  certain  strains  as 
usually  present  when  we  think  '  I,'  we  can  show  why  it  is 
needed  as  a  means  of  making  certain  distinctions,  but  we 
should  not  expect  to  find  anything  more  by  observation  or 
experiment,  —  and  we  do  not. 

The  Continuity  of  the  Self 

Self-identity.  —  Extensions  of  this  empirically  derived 
self-concept  or  other  related  concepts  have  been  developed 
to  solve  certain  of  the  more  theoretical  problems  of  psy- 
chology and  metaphysics.  One  of  the  simplest  of  these  is  to 
answer  the  question  of  how  the  continuous,  ever-changing 
series  of  mental  processes  can  all  be  referred  to  the  same 


THE   CONTINUITY   OF   THE    SELF         573 

self,  are  held  together  in  a  continuous  stream,  and  are 
regarded  as  states  of  the  perceiving  self.  As  a  matter  of 
fact,  the  practical  man  is  never  bothered  by  this  problem. 
In  observation  he  is  concerned  only  with  the  things  that  are 
meant.  It  is  only  in  recognition  that  the  fact  that  he  has 
seen  a  thing  before  is  important  to  him,  and  even  then  he  is 
more  interested  in  knowing  that  the  object  was  in  a  certain 
place  at  a  certain  time  than  in  the  fact  that  he  saw  it 
there.  The  different  experiences  are  held  together  as  parts 
of  a  single  whole  by  the  interrelations  that  make  recognition 
possible,  that  make  it  possible  to  refer  each  experience  to 
a  definite  position  in  the  series.  This  fact  of  reference  is 
immediately  observed.  When  the  self-concept  has  devel- 
oped, the  theorist  makes  that  the  point  of  reference,  in 
spite  of  the  difficulty  in  seeing  how  an  actual  substantial 
something  apart  from  the  experiences  could  hold  them 
together.  If  by  the  self  we  mean  the  experiences  themselves 
as  interrelated  one  to  the  other,  the  notion  offers  less  diffi- 
culty. 

The  Unity  of  Consciousness.  —  Similar  theories  have  sug- 
gested that  the  fact  that  all  of  the  mental  states  form  a 
unity  at  any  moment  can  be  explained  in  terms  of  the  self- 
concept.  Again  it  must  be  insisted  that  what  is  or  can  be 
noticed  is  the  unity,  so  far  as  that  exists,  rather  than  an 
ego.  A  self  in  addition  to  the  states  would  not  give  them 
unity.  Rather  must  the  unity  come  from  the  interconnec- 
tion of  mental  states,  the  subordination  of  all  to  some  single 
one  that  is  the  central  point  of  attention.  As  has  been  seen 
frequently,  many  processes,  some  corresponding  only  to 
partially  aroused  association  paths,  cooperate  in  constitut- 
ing any  single  experience.  In  part  this  unity  is  explained  by 
the  nervous  system,  in  which  many  neurones  are  always 
aroused  together  and  the  action  of  each  produces  a  spread 


574        FUNDAMENTALS   OF  PSYCHOLOGY 

of  impulses  to  all  of  the  others;  in  part  it  is  to  be  referred 
to  the  interrelation  of  what  might  be  regarded  as  single 
elements  in  the  formation  of  concepts  and  meanings,  the 
real  mental  units.  In  any  case  the  unity  is  within  the 
mental  states,  not  a  unity  that  comes  from  without  through 
a  connection  with  some  single  thing.  In  both  of  these 
cases,  as  in  the  more  empirical  active  and  emotional  pro- 
cesses, the  facts  are  to  be  found  in  the  continuity  and  unity 
of  mental  processes ;  the  self-concept  is  developed  or  intro- 
duced to  explain  them.  It  is  merely  a  method  of  picturing, 
not  an  actual  experience.  Here  the  concept  is  even  less 
satisfactory  as  an  explanation  than  it  was  in  the  preceding 
instances. 

In  one  respect  the  more  cognitive  processes  which  are 
explained  by  this  more  passive  type  of  self  may  be  com- 
bined with  the  more  active  discussed  above.  The  system  of 
purposes  which  was  seen  to  be  the  deciding  factor  in  deliber- 
ate action,  and  to  determine  the  character  of  the  emotions, 
is  closely  bound  up  with  the  system  of  knowledge.  Given 
the  instinctive  basis,  each  experience  modifies  that  instinct, 
and  gives  it  definite  content  at  the  same  time  that  it  aids  in 
the  construction  of  our  system  of  concepts  and  prepares  the 
way  for  recognition  and  for  meaning.  In  this  way  the  two 
groups  of  systems  become  closely  interwoven  and  are 
probably  for  the  most  part  merely  differerrt  expressions  of 
the  same  fundamental  unity.  When  active  in  the  control 
of  perception  and  reason,  we  term  the  result  the  cognitive 
processes;  when  acts  and  emotions  are  involved,  we  speak 
of  purposes.  All  education  influences  each  system,  though 
in  different  degrees.  The  system  of  purposes  closely  deter- 
mines the  acquisition  of  knowledge  and  the  use  made  of  it 
in  memory  and  reasoning,  while  the  knowledge  obtained 
has  its  effects  on  the  formation  of  purposes.    It  is  the  close 


DISSOCIATIONS    OF  THE  SELF  575 

interrelation  and  dynamic  interaction  of  all  parts  of  expe- 
rience that  really  give  a  unitary  character  to  the  acts  of  the 
individual,  determine  his  intellectual  interests,  and  make 
possible  the  continuity  of  recognition  and  of  meaning. 

Dissociations  of  the  Self 

Dissociations  of  Personality.  —  That  this  interrelation 
of  all  parts  probably  has  a  physical  basis  is  evident  from  the 
fact  that  in  certain  abnormal  individuals  the  unity  of 
memory  or  knowledge  and  of  purposes  may  be  broken  up 
into  two  or  several  systems,  each  of  which  acts  alone  to 
produce  all  the  capacities  of  a  whole  individual,  but  which 
differ  in  the  characteristics  of  each  of  the  partial  personah- 
tiesj  The  cases  of  alternating  or  dissociated  personality 
offer  much  of  dramatic  interest,  which  cannot  be  treated 
here.  \A  person  who  may  be  in  fair  health  will  suddenly  find 
himself  in  a  strange  situation,  with  no  memory  of  anything 
that  has  happened  before.  In  one  case  even  the  most  rudi- 
mentary knowledge  of  simple  things  was  lost,  and  some  days 
were  required  for  the  patient  to  recognize  simple  objects, 
and  still  longer  to  learn  to  speak.  For  a  long  time  this 
second  set  of  experiences  remained  cut  off  from  the  old,  then 
finally  the  patient  awoke  again  with  no  memory  for  recent 
events,  as  if  he  had  just  waked  up  into  the  first  set  of  expe- 
riences. In  most  cases  the  second  self  comes  into  being 
with  a  portion  of  the  original  memories  and  experiences  of 
the  old.  There  is  a  dissociation  of  the  old  into  two  or  more 
parts,  rather  than  a  development  of  an  entirely  new  series. 
The  patient  suddenly  wakes  in  an  unfamiliar  environment, 
with  no  memories  of  where  he  may  be  or  of  recent  events, 
but  with  full  command  of  language  and  the  abihty  to  inter- 
pret the  objects  about.  After  that  the  different  personalities 
or  groups  of  experiences  will  alternate.    The  time  occupied 


576        FUNDAMENTALS   OF  PSYCHOLOGY 

by  one  self  varies  greatly,  as  does  the  occasion  for  the  change 
from  one  to  another,/ 

Characteristics  of  the  Partial  Selves.  —  If  we  relate  the 
characteristics  in  which  the  selves  vary,  and  the  marks 
that  distinguish  them  one  from  the  other,  to  the  facts  that 
have  led  to  the  development  of  the  self-concept,  we  find 
that  practically  all  of  them  may  be  closely  paralleled.  One 
element  in  the  consciousness  of  self  is  the  persistence  of 
various  organic  sensations.  One  feels  at  home  in  the  body, 
if  we  may  indulge  in  metaphor,  because  the  strain  sensations 
are  constant  from  one  time  to  another.  Ribot  reports  some 
cases  of  split  personality  in  which  the  organic  sensations 
were  changed,  arid  suggests  that  the  change  might  in  part 
have  accounted  for  the  alteration.  Much  more  important 
is  the  break  in  the  line  of  association,  the  inability  to  recall 
an  event  in  one  state  which  has  occurred  in  another.  The 
train  of  memories  seems  to  be  broken  off  sharply  when  the 
personality  alternates.  Everything  that  happened  in  one 
state  can  be  recalled  in  that  state,  but  all  the  experiences 
of  the  other  state  are  lost.  There  is,  furthermore,  no  recog- 
nition in  one  state  of  the  objects  seen  in  another.  The  asso- 
ciations that  connected  them  originally  are  completely 
broken,  while  the  associations  within  each  group  persist. 
It  is  this  characteristic  that  gives  the  name  of  dissociated 
personality.  In  the  dissociation  there  SQem  to  be  pccuhar 
divisions  of  the  original  self.  In  the  Beauchamp  case, 
reported  by  Dr.  Prince,  one  self  kept  the  knowledge  of 
French  of  the  original,  while  the  others  were  entirely  with- 
out it;  and  other  acquirements  seemed  to  be  assigned  to 
orie  alone  of  the  personalities. 

Not  merely  are  the  acquirements  differently  divided,  but 
the  active  and  emotional  characteristics  seem  also  to  vary. 
One  self  will  be  highly  conventional  in  action  and  desires, 


ori< 


DISSOCIATIONS    OF   THE  SELF  577 

will  respond  very  quickly  to  social  instincts,  the  other  will 
be  entirely  arbitrary  in  action.;  The  difference  may  ap- 
proach that  so  vividly  pictured  by  Stevenson  in  his  story 
of  Dr.  Jekyll  and  Mr.  Hyde.  i^The  purposes  of  the  two  selves 
are  different,  as  are  also  the  memories.j  This  is  in  accordance 
with  our  explanation  of  the  development  of  ideals  by  the 
action  of  the  accumulated  experiences.  When  the  systems 
of  knowledge  divide,  the  control  exerted  by  each  of  the 
two  sets  of  ideals  or  purposes  is  exerted  differently  according 
to  the  components  that  make  it  up.  /  Dr.  Prince  suggests 
that  in  certain  cases  the  instincts  as  well  seem  to  be  divided. 
One  self  will  take  most  of  the  tender  and  benevolent  in- 
stincts, the  other  most  of  the  aggressive,  the  rebellious, 
anti-social  instincts.  Where  one  self  will  be  painfully  con- 
scientious and  considerate  of  others,  the  second  will  be 
altogether  selfish  and  indifferent  to  the  ordinary  family  and 
social  welfare.  With  the  break  in  knowledge,  there  goes  a 
corresponding  sudden  alternation  in  the  effective  self.  The 
individual  shows  different  emotions,  is  differently  controlled 
in  action  and  in  thought.  Aside  from  the  fact  that  both 
selves  are  still  in  the  same  body,  they  are  essentially  two 
individuals,  two  selves.]  There  is  no  memory  or  recognition 
of  events  that  occur  to  the  other  self,  there  is  no  consistency 
of  action  between  them,  there  is  no  continuous  self-con- 
sciousness from  one  to  the  other.  Both  the  theoretical  and 
practical  characteristics  of  the  two  selves  are  altered. 

The  Phenomenon  of  Dissociation.  -^  If  we  attempt  an 
exjjlanation  from  the  ph}^sical  side,  it  would  seem  that  the 
various  effects  upon  the  nervous  system  are  retained  and 
organized  into  systems ;  that  these  systems,  while  ordinarily 
acting  as  units,  may  by  certain  shocks  be  dissociated  along 
somewhat  definite  Unes  of  cleavage  that  also  develop  as  a 
result  of  the  formation  of  distinct  systems.     When  the 


578        FUNDAMENTALS  OF  PSYCHOLOGY 

break  comes,  we  have  each  system  or  group  of  systems 
persisting,  but  with  no  bonds  of  connections  between  them. 
Each  system  continues  to  act  alone,  and  to  control  the 
responses  through  the  persistent  nervous  connections, 
guided  by  the  wider  series  of  partially  active  neurones. 
In  most  cases  certain  of  the  more  frequent  nervous  activiHes 
are  common  to  the  two  systems,  but  this  shows  itself  only 
in  the  persistence  of  the  nervous  correlates  of  more  general 
concepts  and  ideas,  to  which  each  of  the  new  experiences 
may  be  referred  and  be  understood,  with  none  of  the  more 
specific  references  that  constitute  recognition.  The  normal 
self  has  as  its  correlate  on  the  physical  side  a  complete 
system  or  system  of  systems,  from  all  of  the  more  important 
parts  of  which  impulses  may  pass  to  awaken  all  of  the  other 
parts,  —  a  system  that  embraces  and  unifies  many  lesser 
systems,  all  of  which  are  connected.  So  long  as  this  system 
remains  unbroken,  memory  is  continuous,  memories  from 
all  parts  of  the  life  may  be  recognized,  and  the  actions  are 
sufficiently  controlled  to  be  consistent.  That  this  is  the 
basis  for  the  characteristics  that  we  have  regarded  as  con- 
stituting the  peculiar  condition  of  the  self  is  evident  from 
the  fact  that,  when  this  complete  system  is  broken  into 
two  or  more  groups  of  systems,  two  or  more  selves  make 
their  appearance. 

Hypnotism  and  Other  Forms  of  Dissociation.  — [Not 
only  does  dissociation  arise  spontaneously,  but  in  many 
individuals  it  may  be  induced  at  will.  If,  for  example, 
a  patient  be  asked  to  keep  attention  continuously  fixed 
upon  some  one  object,  he  will  pass  into  a  cataleptic  stage, 
his  muscles  will  stiffen,  and  he  will  gradually  to  all  appear- 
ances become  unconscious,  and  in  the  higher  degrees  of  the 
resulting  abnormal  condition  will  show  many  of  the  phases 
of  the  dissociated  personality.     The  state  is  much  more 


THE  SELF  AS  THE  WHOLE  MAN  ACTIVE     579 

readily  induced  if  the  patient  remains  passive  and  is  told 
from  time  to  time  that  he  is  going  to  sleep,,  _When  most 
completely  hypnotized,  the  patient  is  highly  suggestible, 
will  do  anything  that  he  is  told  to  do,  may  even  be  made 
to  take  on  different  personalities.  On  waking  there  is 
ordinarily  no  memory  of  what  has  happened  during  the 
hypnotic  state,  although  when  hypnotized  again,  the  person 
may  recall  the  events  of  this  period.  The  close  relation 
between  this  and  the  phenomena  of  the  dissociated  self  is 
indicated  by  the  fact  that  change  from  one  self  to  the  other 
often  can  be  induced  by  suggestion  in  the  hypnotized  state 
and  that  when  hypnotized  in  one  state,  that  self  will  recall 
events  experienced  in  other  states.  \  In  many  diseased 
conditions  there  is  evidence  that  partial  dissociation  of 
these  systems  may  take  place  and  may  be  responsible  for 
the  disease.  Hysteria  is  largely,  if  not  altogether,  due  to 
a  breaking  away  from  the  whole  of  some  one  of  the  systems. 
This  may  not  be  large  enough  seriously  to  disturb  the  higher 
coordinations  of  the  self,  but  does  prevent  the  larger  system 
from  receiving  impressions  from  certain  sense  organs  con- 
nected with  the  dissociated  elements,  and  may  also  cause 
a  paralysis  of  the  muscles  that  are  either  permanently  or 
temporarily  united  with  those  dissociated  elements. 

The  Self  as  the  Whole  Man  Active 

Consciousness  and  Subconsciousness.  —  Numerous 
theories  have  suggested  that  the  self  is  seldom  completely 
united,  that  there  are  always  larger  or  smaller  groups  of 
experiences  or  memories  which  are  independent  of  the 
larger  system.  Thus,  Freud,  as  we  have  seen,  explains 
dreams  and  many  of  the  accidents  of  daily  life  as  well  as 
the  witty  sayings  of  the  normal  individual  by  the  fact  that 
he  has  an  organized  complex  of  elements,  which  usually 


58o        FUNDAMENTALS   OF  PSYCHOLOGY 

contributes  little  to  consciousness  but  which  on  occasion 
will  be  excited  and  when  aroused  open  new  possibilities 
for  good  or  evil  in  the  individual.  This  detached  complex 
is  frequently  said  to  have  all  of  the  elements  of  the  normal 
or  total  self,  to  have  desires  of  its  own,  to  do  thinking  for 
itself,  —  in  fact,  to  constitute  a  true  self,  which  is  also 
regarded  as  having  a  kind  of  consciousness.  Many  facts 
point  to  the  presence  of  these  complexes,  and  the  assertion 
that  a  definite  consciousness  attaches  to  them  raises  many 
questions  as  to  what  our  ordinary  consciousness  may  be, 
upon  what  it  depends.  It  must  be  granted  that  these 
subconscious  systems  give  rise  to  many,  if  not  all,  of  the 
effects  of  the  complete  system.  We  could  personify  them 
as  readily  as  we  do  the  experience  of  many  other  individuals. 
The  only  test  of  consciousness  from  the  inside,  however, 
is  the  personal  test  —  that  we  are  aware  of  it  in  intro- 
spection —  and  by  definition  this  subconscious  does  not 
belong  to  that  class. 

However,  so  many  of  the  determinants  of  our  personal 
consciousness  are  not  themselves  directly  conscious  that 
the  difference  may  not  be  important.  Of  all  of  the  myriad 
activities  in  the  nervous  system,  only  a  few  can  be  known 
at  any  moment;  and,  as  has  become  apparent  from  the 
study  of  meaning  and  related  processes,  no  one  of  these  is 
consciousness,  of  and  for  itself  alone.  It  must  always 
be  grouped  with  a  number  of  other  activities,  if  conscious- 
ness is  to  result.  Even  then  consciousness  is  limited,  in 
most  cases,  to  the  things  referred  to  or  meant,  rather  than 
to  the  elements  that  are  supposed  to  carry  the  meaning. 
Each  group  of  nervous  elements  may  by  its  activity  con- 
tribute to  the  consciousness  of  the  total,  but  the  conditions 
of  consciousness  must  still  be  regarded  as  obscure.  The 
most  that  can  be  said  is  that  of  the  different  systems  which 


THE  SELF  AS  THE  WHOLE  MAN  ACTIVE     581 

are  found  within  the  nervous  system  at  any  one  time,  the 
largest  and  most  active  is  accompanied  by  consciousness. 
The  others  are  either  completely  suppressed,  as  in  the  case 
of  the  complexes  of  the  subconscious  or  unconscious,  or 
the  minor  systems  contribute  only  in  some  slight  degree 
to  the  total  consciousness.  Consciousness  seems  to  be 
determined  by  or  to  accompany  the  activity  of  a  system 
of  nervous  elements,  connected  by  virtue  of  acting  together 
in  various  systems  of  experiences.  How  many  elements 
may  be  included  in  what  corresponds  to  the  centre  of  con- 
sciousness, and  how  far  less  central  elements  can  play  a 
part,  no  one  can  say.  It  can  be  asserted  with  assurance 
that  even  the  most  central  features  of  consciousness  cor- 
respond to  the  action  of  many  neurones,  show  the  effect  of 
many  experiences,  and  represent  even  more.  Where  the 
limits  are  to  be  drawn  is  not  to  be  confidently  stated. 

The  Self  and  the  Individual.  —  Very  little  of  the  nervous 
action  is  really  accompanied  by  consciousness,  although 
a  very  large  part  of  that  activity  has  an  effect  upon  con- 
sciousness. Much  the  same  statement  may  be  made  of  the 
functions  of  the  individual,  as  we  deal  with  him  in  psychol- 
ogy and  everyday  life.  We  know  that  he  remembers  and 
recognizes,  that  he  perceives  objects,  and  reaches  con- 
clusions, that  he  feels  and  chooses;  we  can  even  trace  many 
of  the  conditions  of  these  different  operations,  but  he  him- 
self is  conscious  of  little  more  than  the  outcome,  —  the 
causes  are  not  revealed  in  consciousness.  There  is  no  oc- 
casion, then,  to  spend  much  time  on  the  question  whether 
some  of  the  hidden  complexes  of  neural  activities  are  accom- 
panied by  consciousness,  when  we  know  so  Uttle  of  the 
causes  and  effects  of  the  highest,  most  fully  revealed 
consciousness. 

A  close  analysis  of  self-consciousness  gives  as  little  re- 


582        FUNDAMENTALS  OF  PSYCHOLOGY 

ward.  One  has  certain  concepts  which  are  represented 
by  more  or  less  definite  imagery,  but  again  the  important 
factor  is  not  the  imagery  but  what  the  imagery  represents. 
This  is  our  notion  of  the  whole  as  active,  of  the  processes 
that  direct  our  thoughts  and  acts,  a  continuous  experience, 
with  the  possibihty  of  referring  from  any  part  to  any  other. 
All  these  are  involved  in  the  self  idea,  but  are  not  all  con- 
scious at  any  time.  The  consciousness  of  self  is  seldom 
present  and  is  of  Httle  importance  when  present,  the  self 
as  the  whole  man  active,  as  the  unity  and  continuity  of 
experience,  is  fundamental.  It  must  be  emphasized  that 
this  is  not  a  single  experience  among  the  other  experiences, 
it  is  not  something  of  which  we  may  become  immediately 
conscious;  on  the  contrary  it  is  the  man  with  all  of  his 
experiences  and  activities  viewed  as  a  whole. 

REFERENCES 

James:  Principles  of  Psychology,  Vol.  I,  Chs.  IX,  X. 
Cooley:  Human  Nature  and  the  Social  Order. 
Ribot:  The  Diseases  of  Personality. 
Prince:  The  Dissociation  of  a  Personality. 


INDEX  OF   NAMES 


Ach,  529,  531,  537. 

Cooley,  582. 

Alriitz,  160/. 

Courtier,  472. 

Angell,  Frank,  3Q0. 

Craig,  W.  C,  225. 

Angell,  J.  R.,  14,  327. 

Cushing,  66. 

Arai,  541. 

Aristotle,  246. 

Dalton,  116. 

Aronsohn,  178. 

Darwin,  437/,  4Q4/,  So7- 

Aschaffenburg,  284. 

Davies,  170. 

Atwood,  546. 

Dawes-Hicks,  333. 

Descartes,  480/. 

Bagley,  W.  C,  361. 

Dewey,  440,  497- 

Bair,  386,  S13,  515,  537- 

Diamandi,  403. 

Barany,  58. 

Dodge,  262,  364,  542. 

Barrett,  532/- 

Dallenbach,  367. 

Batson,  518. 

Donaldson,  158. 

Berussi,  356. 

Dunlap,  92. 

Berman,  507. 

Bczold,  154. 

Ebbinghaus,  198,  286,  368,  369,  370 

Biedermann,  196. 

371,  376,  378,  380/,  386/,  398. 

Bills,  Marian,  126. 

Edelmann,  143. 

Bing,  92. 

Ellis,  Havelock,  452. 

Blix,  158. 

Erdmann,  364. 

Book,  515. 

Boring,  170. 

Fabre,  220. 

Bourdon,  311,  343. 

Fechner,  11,  194,  19S,  i97,  245- 

Breed,  234. 

Ferree,  347,  349. 

Breuer,  183. 

Flechsig,  68. 

Broca,  64-70. 

Flourens,  64. 

Brown,  Crum,  183. 

Franz,  69,  514 

Brown,  Thomas,  181. 

Freud,  446/,  457,  502,  579- 

Brum,  143. 

von  Frey,  160,  162,  164,  167,  182 

Bryan, 515,  517. 

197,  302. 

Burdach,  42  /. 

Galen,  505,  507. 

Caesar,  274. 

Gall,  63. 

Calkins,  ATary  W.,  286. 

Galton,  211,  259,  264,  286. 

Cannon,  188,  487,  490/- 

Goddard,  210. 

Carlson,  188. 

Goldscheider,  158,  162,  164,  181  / 

Charcot,  259. 

302. 

Chevreul,  170. 

Goll,  63. 

Claparede,  557. 

Gowers,  44. 

Clifford,  90. 

Gray,  364. 

Coleridge,  383. 

Greenwood,  135. 

Colvin,  406. 

Griffitts,  261,  542,  550. 

». 


583 


< 


584 

Hardesty,  156. 
Harter,  515,  517. 
Haycraft,  179. 
Hayden,  390. 
Hayward,  390. 
Head,  164,  16S,  170. 


INDEX   OF   NAMES 


ti6,  123,  128,  129, 
53,  157,  191.  343- 

116,    123,   132  /, 


Heller,  328. 
Helmholtz,  112/ 

131,  134/,  151, 
Henning,  17S  f,  i 
Hensen,  155. 
Hering,  82,   112,   i: 

159,  244,  307- 
Hermann,  145. 
Herrick,  59,  92. 
Hobbes,  93. 
Hobhaus,  220. 
Hodge,  545. 
Hollingworth,  390. 
Howell,  59,  135,  157 
Huey,  364. 
Hunter,  347,  349. 


Inaudi,  403. 

James,  240,  343,  356,  413,  435,  484, 

4867,491,  507,  525,  569,  582. 
Jastrow,  420,  507. 
Jennings,  18,  512. 
Jost,  375,  377/. 
Judd, 3S3. 

Kent,  248. 

Kiesow,  175. 

Koehler,  145. 

Koenig,  145. 

Kraepelin,  539,  541. 

KreidI,  186. 

von  Kries,  116,  123,  13,3  ff. 

Kulpe,  255/,  414,  464. 

Ladd,  92,  157,  181,  343,  356,  537. 

Ladd-Franklin,  Mrs.,  135. 

Lange,  484. 

Langefeld,  524. 

Langley,  197. 

Lasher,  514. 

Lee,  559. 

Leonardo  da  Vinci,  113. 

Lewis,  542,  544,  546,  550. 

Liepmann,  75. 

Lipps,  477. 

Locke,  93,  339. 


Long,  Constance,  457. 
Lotze,  300/. 
Lowitt,  196. 
Luft,  143. 

MacDougall,  W.,  92,  224,  240,  251, 

264,  480,  493,  504. 
Mach,  183. 
Malthus,  438. 
Marshall,  H.  R.,  479. 
Martin,  Lillien  J.,  256. 
Mayer,  149. 
Meumann,  371,  374,  375,  379,  398, 

402  /,  406. 
Meyer,  Adolf,  71. 
Meyer,  Ma.x,  156. 
Meyer,  S.  C,  395. 
Michotte,  531/. 
Mill,  iSi. 

Muller,  G.   E.,  133,  198,  245,  369, 
^m,  379,  382,  385,  399,  406,  559. 
Muller,  H.,  107. 
Muller,  Johannes,  311. 
Monakow,  von,  92. 
Morgan,  J.  B.,  276,  293. 
Morgan,  Lloyd,  217,  240. 
Mosso,  544. 
Mulhall,  Miss,  390. 
Muscio,  559. 
Myers,  135,  157,  263,  327,  356. 

Nagel,  192.  ' 

Oehrwall,  173. 
Ogden,  378. 

Parsons,  135. 

Pawlow,  472,  487. 

Pearson,  211. 

Perkins,  Nellie,  376. 

Pieron,  557,  559. 

Pillsbury,  182,  240,  293,  364,  440. 

Pilzecker,  245. 

Piper,  36. 

Plato,  421,  484. 

Prince,  Morton,  577/,  582. 

Priim,  532. 

Pulfrich,  311. 

Pyle,  374 

Radossawljcwitsch,  387,  397, 
Rayleigh,  Lord,  326. 
Ribot,  507,  582. 


INDEX   OF   NAMES 


585 


Rivers,  168,  170,  457   557. 
RosanolT,  248. 
Royce,  467  _ff. 
Ruckle,  399,  402. 
Russell,  Bertrand,  14. 
Rutherford,  155. 

Sanford,  379. 

Schaeffer,  92. 

Schaeffer,  H.,  157. 

Schumann,  369,  379,  382,  385. 

Scriabin,  263. 

Shand,  4S0  /,  507. 

Shepard,  385,  450,  472,  556,  559. 

Sherrington,    79,    d^zj,    487,   490/, 

498. 
Skaggs,  379. 
Sollier,  485. 
Spinoza,  481. 
Spurzheim,  63. 
Stefifens,  Miss,  373/. 
Stern,  345. 
Stewart,  326. 
Stout,  477,  504. 
Stratton,  304. 
Streeter,  58,  186. 
Strieker,  260,  264. 
Strong,  C.  A.,  92. 
Strong,  E.  K.,  390. 
Swift,  515,  537. 

Terman,  203/. 
Thorndike,  511. 
Thunberg,  161. 
Titchener,  135,  181,  267/,  293,  356, 

440. 
Trotter,  170. 


Ulrich,  376. 
Urbantschisch,  149. 

Villiger,  59. 
Vogelsonger,  385. 
Volkmann,  302. 

Wallace,  437ir. 

Waller,  19S. 

Warren,  14,  479. 

Watson,  6,  14,  224,  240,  250,  507, 

513- 
Watt,  157. 
Weber,  195. 
Wernicke,  70. 
Wheatstone,  320. 
Wien,  196/. 
Wirth,  268. 
Witasek,  343,  379. 
Wohlgemuth,  349. 
Wolfe,  389  /,  398. 
Wolff,  II. 
Wood,  21  r. 
Woodrow,  3SO,  352. 
Woodworth,  14,  92,   157,  181,  264, 

268,  343,  356,  414,  457,  475, 477, 

521,  537- 
Wundt,  II,  197,  266,  268,  304,  332, 

468/,  472,  505. 


Yerkes,  218. 
Yoakum,  218. 
Young,  112,  116, 
Yule,  209. 


131- 


Zander,  176. 
Zeitler,  357. 
Zwaardemaaker,  181. 


SUBJECT   INDEX 


Abnormal  psychology,  13. 
Accommodation  in  the  perception  of 

depth,  314;   mechanism  of,  loi /. 
Achromatic  series,  iigjf. 
Acquisition  of  skill,  515-520. 
Action,  508-537. 
Adaptation,  visual,  120/,  126. 
Adrenal    glands,    87;     in    emotion, 

488/. 
Affection  and  feeling,  458  J";  bodily 

changes  in,  471  ff;  not  sensation, 

460-464;  qualities  of ,  466  .^. 
After-images    in    movement,    346; 

negative,  117;  ringing  off  of,  128. 
Anatomy  and  psychology,  8  /. 
Angle  illusions,  335/. 
Animal  psychology,  12. 
Aphasia,  70  Jf. 
Apraxia,  74/. 

Areas,  minimum  visual,  130. 
Association,    246-252;     control    of, 

284-289;  laws  of ,  246 ^;  nervous 

basis  of,  249  /. 
Attention,  265-294;    and  intensity, 

266  /;     conditions   of,    277-284; 

effort  and,  289;  forms  of,  288-291; 

nature   of,    265  /;    physiological 

basis  of,  291;  range  of,  273/. 
Attributes  of  sensation,  95  /. 
.'\udition,  limits  of,  142  /. 
Auditory  nerve,  connections  of,  53. 
Auditory   space,    325-329;     in    the 

blind,  328. 
Autonomic  nervous  system,  84  /. 
Axone,  22/. 

Basilar  membrane  142,  151/. 

Beats,  146. 

Behaviorism,  6/. 

Behavior  of  lower  organisms,  15  Jf. 

Belief,  430/. 

Binocular  vision,  309  jf. 

Body  and  mind,  relation  of,  88  J'. 


Born    blind,    space    perception    of, 

337/- 
Brain,  development  of,  ss  f. 
Brain  stem,  functions  of,  46/;  paths 

in,  48/;  structures  of ,  47 /. 

Cerebellum,  57/. 

Cerebral  localization,  62  f. 

Cerebrum,  parts  of,  60/. 

Character,  201. 

Character  tests,  207  /. 

Child  study,  12. 

Chinese  symbols  as  concepts,  418. 

Choice,  528-531. 

Circulation,  changes  of,  in  affection, 

472/. 
Clearness  and  attention,  267/. 
Cochlea,  structure  of,  140/. 
Coefficient  of  correlation,  208  /. 
Cognition  and  recognition,  396/. 
Cold  spots,  158/. 
Color  blindness,  115  ff. 
Color  mixture,  in  /. 
Color  pyramid,  logjf. 
Complementary  colors,  14/. 
Concept,  414-424;    and  perception, 

362  ff;    self  as,  561  f;    space  as, 

341/- 
Concepts,   development   of,   417  /; 

use  of  in  reasonifig,  422/. 
Conditioned  reflex,  250. 
Cones,  104/;  contraction  of,  108. 
Confluxion  and  contrast  as  theory  of 

illusion,  334. 
Consciousness,  4  ff;  and  movement, 

520/;  unity  of,  573. 
Consonants,   Hehnholtz   theory  of, 

148. 
Contrast,  118. 
Control  of  emotions,  501. 
Convergence  in  perception  of  depth, 

315/- 
Cord,  reflexes  in,  39  ff. 


586 


SUBJECT   INDEX 


587 


Corpora  quadrigemina,  function  of, 

59- 
Corresponding  points,  310. 
Cortex,  association  areas  in,  68  Jf; 

motor  areas  in,  65  /;  sensory  areas 

in,  66  /. 
Cutaneous  sensations,  157-17°;  sense 

organs,  166  Jf. 

Deduction,  433. 

Definitions  of  psychology,  3  /. 

Dendrite,  22/. 

Depth,  perception  of,  314-324. 

Deuternope,  124  Jf. 

Distraction  and  attention,  276. 

Distributed  repetitions  in  learning, 

375/- 

Double  images,  316/. 

Drainage,  law  of,  250/. 

Dreams,  448-451. 

Ductless  glands,  85  /;  in  tempera- 
ment, 506/. 

Duplicity  theory,  120  Jf. 

Duration  of  sensation,  96  /. 

Ear,  structure  of,  gS  ff. 

Economics  and  psychology,  10. 

Education  and  attention,  281. 

Effort  as  muscular  strain,  271. 

Emotion,  480-508. 

Emotions,  classification  of,  498  /; 
in  self,  568  /. 

Empathy,  477. 

Empiricism,  338-341. 

Epicritic  sensibility,  169. 

Evolution,  discovery  of  as  illustra- 
tion of  reasoning,  437  /. 

Extent  of  sensation,  96/. 

Eye,  dioptrics  of,  102  f;  structure 
of,  98/. 

Eye-movements,  307  /. 

Eye-muscles,  306  /. 

Facilitation  and   attention,    291  f; 

of  nervous  impulses,  81/. 
Fatigue,   538-556;     bodily   changes 

in,  548  /;   mental,  546  /. 
Fears,  instinctive,  226/. 
Feeling,  458-480;    theories  of,  474- 

478- 
Fifth  nerve,  connections  of,  53  /. 
Fissure  of  Sylvius,  development  of, 

34/. 


Flcchsig,  tracts  of,  43  /. 
Fluctuations  of  attention,  274  /f. 
Forgetting,  curve  of,  3S0/;    Freud's 

theory  of,  452. 
Fovea,  106  Jf. 

Freedom  of  the  will,  534-537. 
Fusion,  tonal,  147/. 

Genetic  psychology,  12. 
Goal  idea,  284  /. 
Goll,  columns  of,  42/. 
Gregariousness,  229/. 

Habit,  and  the  synapse,  80;  forma- 
tion of,  212  Jf. 

Hearing,  theories  of,  151. 

Helmholtz  theory  of  color,  131. 

Hemispheres,  development  of,  35/. 
'T^eredity,  and  attention,  283  /; 
mental,  199/. 

Hering  theory  of  vision,  132/. 

Horopter,  312  ff. 

Hunger,  188. 

Hypnotism,  578/. 

Imageless  thought,  413  .f- 

Imagery  tjT^es,  258-263;  and  mem- 
ory, 402  /,•  concrete  types  of, 
201/;  verbal,  260/. 

Images,  mental,  254-258;  projec- 
tion of,  256/. 

Imagination,  441-457. 

Imitation,  235/;   in  learning,  519/. 

Incentives  in  movement,  522  /. 

Individual  differences  in  memory, 
401. 

Induction,  435  /. 

Industry,  fatigue  in,  548/. 

Inference,  427-430. 

Inheritance,  mental,  210^. 

Inhibition  and  attention,  291  /; 
associative,  379;  of  nervous  im- 
pulses, 82  /;  reproductive,  385  /; 
retroactive,  382. 

Instinct,  219-241;  classification  of, 
224  /;  definitions  of,  219  Jf;  in 
learning,  234  /;  in  the  control  of 
habit,  216;  origin  of,  237-240;  of 
infancy,  225/;  social,  229-233. 

Intelligence,  201  Jf;  distribution  of, 
204  /;  tests,  202  /;  quotient, 
203/. 

Intensity  of  sensation,  96. 


588 


SUBJECT   INDEX 


Interactionism,  89. 
Interest  and  attention,  290. 
Introspection,  2/. 
Irradiation,  129. 

James-Lange    theory    of    emotion, 

484/. 
JosTsLaw,  377,  382. 
Judgment,  424-427. 

Kineesthetic  sensations,  181  /. 

Ladd-Franklin  Color  Theory,  133. 

Language,  development  of,  235  /. 

Learning  in  animals,  511  /;  Laws 
of  rote,  369-380;  by  wholes  pref- 
erable, 373/- 

Limen  of  twoness,  301  /. 

Localization,  spatial,  theories  of, 
305  /;  cerebral,  63-69. 

Meaning,  410-414;   and  movement, 

522;  and  recognition,  395. 
Memory,     365-407;      after-image, 

244/;  image,  244;  systems,  404/; 

Training    of,    405;     Methods    of 

investigating,  368  /. 
Mental  age,  203. 
Methods  of  psychology,  2  /. 
Mimetic  movements,  270. 
Mind,  3  /. 
Mood,  504. 
Motion  and  aid  to  depth  perception, 

323./"- 
Motor  phenomena  m  attention,  26S- 

272. 
Movement  and  perception,   296  /; 

and  sensation,  509 
Miiller-Lyer  illusion,  331  /. 
Myths,  symbolism  in,  453. 

Nativism,  as  theory  of  space,  338- 
341- 

Nerve  impulse,  theory  of,  37#. 

Nervous  system,  15-93;  develop- 
ment of,  27/;  parts  of,  24/._ 

Neurones,  structure  and  functions 
of,  20  _^. 

Noise,  nature  of,  150/. 

Observation,  2/. 
Observational  memory,  366  f. 
Olfactory  sensations,  176-181. 


Optic  nerve,  connections  of,  $2>- 
Optical  illusions,  329-337. 
Organic  sensations,  188^. 
Origin  of  emotions,  494  ff. 

Pain,  sensations  of,  162  jf. 

Perception,  294-364;  and  associa- 
tion, 294  /;  as  concept,  295  /;  of 
space,  298-344. 

Peripheral  vision,  116. 

Perseveration,  245/;  and  distributed 
repetitions,  377;  and  forgetting, 
382;  in  retroactive  inhibition,  382. 

Perspective  in  depth  perception,  322. 

Phase  difference  in  perception  of 
direction  of  sounds,  326. 

Philosophy  and  psychology,  10. 

Physiological  psychology,  11. 

Pituitary  body,  86  /. 

Play  as  instinct,  236  /;  imagination 
and,  442  /. 

Pleasure  as  guide  to  learning  217. 

Practice,  540. 

Pressure,  sensations  of,  160  Jf. 

Primary  colors,  112/. 

Proof,  433,  437- 

Protanope,  125/. 

Protopathic  sensibility,  169. 

Pseudoscope,  319. 

Psychophysical  parallelism,  89  /. 

Pupillary  reflexes,  56/,  100/. 

Purkinje  phenomenon,  122/. 

Purpose  as  condition  of  attention, 
279;  as  sine  qua  non  of  emotion, 
482. 

Pyramidal  tract,  44  /. 

Quality  of  sensation,  96. 


Reading,  357-360. 

Reasoning,  407-440;  active  stages 
in,  409. 

Recall,  384-387. 

Recognition,  387-397;  association 
theory  of,  391  Jf;  motor  theory  of, 
394;  feeling  theory  of,  395. 

Reflex,  determination  of,  38  /. 

Reflexes  in  the  brain  stem,  56/. 

Remote    sensations    in    movement, 

525/- 
Resident   sensations  in   movement, 
526/. 


SUBJECT   INDEX 


589 


Restitution  of  cerebral  functions, 
76. 

Retention,  242-246;  nature  of, 
242/;  and  habit,  243  /;  and  for- 
getting, 380-384. 

Retina,  structure  of,  104/7". 

Retinal  image,  formation  of,  102/. 

Revery,  444-446. 

Rhythm,  340/;  in  learning,  372/. 

Righthandcdness,  74  /. 

Rods,  104/. 

Rote  memory,  368-387. 

Seasickness,  187. 

Selection,  attention  as,  268. 

Self,  560-582. 

Sensation,  93-198. 

Sensations,   classification   of,   04  /; 

intensity  of,  193  /;   intensity  and 

affection,  470;    centrally  aroused, 

254-258. 
Sentiment,  503/. 

Shadows  in  depth  perception,  324/. 
Sight,  sensations  of,  97-135. 
Sleep,  556-560. 
Smell,  sensations  of,  178/. 
Social  forces  in  attention,  282/. 
Social  pressure,  23  2  /. 
Social  psychology,  12;  factors  in  the 

self,  567/. 
Sociology  and  psychology,  10. 
Space  perception,  theories  of,  337- 

343- 
Spatial  phenomena  of  vision,  129. 
Specific  energies,  doctrines  of,  94  JJ, 

iQo/. 
Spectral  colors,  m  Jf. 
Spectrum,  range  of,  07  /. 
Speech,  perception  of,  360. 
Static  sense,  183-185. 
Stereoscope,  318/. 
A  Suggestion,  246. 
Syllogism,  434/- 
Symbolism  in  dreams,  448/. 
Sympathetic    system    in    emotions, 

487/. 
Sympathy,  230/. 


Synaesthesia,  263/. 
Synapse,  40,  77/. 

'T'-.shaped  cells,  32/. 

Tactual  space,  299  Jf. 

Taste,  sensations  of,  170-176;  sense 
organs  of,  172/;  nerves  of,  176; 
and  chemical  composition,  173. 

Teleostereoscope,  3  20  /. 

Telephone  theories  of  hearing,  155//". 

Temperament;  201,  505. 

Temperature,  sensations  of,  158  J[; 
scale,  160  Jf. 

Temporal  phenomena  in  vision, 
126/. 

Tests,  Binet,  202^;  Army,  205/. 

Thalamus,  functions  of,  59. 

Thirst,  189. 

Thyroid  gland,  86. 

Timbre  as  aid  to  perception  of  direc- 
tion of  sounds,  327. 

Time,  perception  of,  352,  356. 

Tonal  qualities,  142  Jf. 

Tone,  sensations  of,  136-157;  color, 
144/. 

Tones,  difference,  149  /. 

Tracts  in  cord,  42  Jf. 

Trial  and  error  in  learning  a  move- 
ment, 510-520;  mental  processes, 
213/- 

Unconscious,  the,  Freud's  theory  of, 
446-451. 

Vesicles,  brain,  34. 

Vestibule,  structure  of,  183/. 

Vision,  stimulus  for,  97. 

Visual    movement,    perception    of, 

344-349. 
Visual  purple,  108. 
Vowels,  qualities  of,  145/. 

Warm  spots,  isSJf. 
Weber's  Law,  193-199. 
Wit.  Freud's  theory  of,  453/. 
Witness,  memory  of,  366]^. 
Work,  538. 


\ 

14  DAY  USE 

RETURN  TO  DESK  FROM  WHICH  BORROWED 

This  book  is  due  on  th^tastdatl  stamped  below,  or 

on  the  date  to  which  renewed. 

Renewed  books  are  subject  to  immediate  recall. 

7  DAY  0!' 

DURING 

SUMMER 

i:.;bS10NS 

1 

■' 

TcliiSSlie"                   vJS^^... 

1U(j 

■  fJ      Ji  "V>*^ 

UC   BERKELEY  LIBRARIES 

lUlliiil "  "■ 


CD5TMfl75flT 


i 


